[center][b][i]On The Cusp
Chapter 5 - Working Theory[/i][/b][/center]


Casey had started yesterday with his usual schedule of self-doubt, denial, and repression. But today? Today all of that felt like it was finally gone. Though, in his limited experience, the few good days he’d had were always rapidly followed up by bad ones.

During the night, his dreams had been less defined than normal. Most of what he was able to remember contained only flashes of emotion and glimpses of light and color, rather than distinct memories or recognizable imagery. And yet… he felt lighter as he woke, the sleep leaving him more refreshed and eager than most mornings. Maybe yesterday had been a turning point for him. 

Glancing over at Raph across the room, he couldn’t help but smile to himself. The bulky turtle was spread out like a starfish on his modified queen mattress, so damn old it was only barely able to prop his limbs up. Because of the size of their shells, Donnie had modified each of their already worn down mattresses to allow for a sizable divot to form in the middle with the press of a button, letting them sink into the mattress and more evenly distribute their weight across their shells without being propped up by them.

Despite this, Raph’s arms were thrown about, one hanging off the side pointing in Casey’s direction, fingers twitching slightly every few seconds. His legs were tangled up in a mixture of the silky sheets April had gotten all of them for Christmas a few years ago, along with the weighted blanket Casey had purchased as a gift for Raph’s birthday.

The turtle groaned slightly and shifted on the bed, causing a worrisome amount of protesting squeeks to emanate from beneath him. But as he settled, Casey spied a very prominent bulge sprouting from between Raph’s thighs and he had to stomach a chuckle. It seemed Raph and he had similar problems in the mornings. 

Maybe he’s dreaming of me. 

Slowly, Casey rose from his makeshift bed as quietly as he could and stood up, wobbling slightly as he stretched, popping his joints and cracking his neck a few times with a sigh. Raph murmured slightly again and Casey took it as a sign that his boyfriend was on the threshold of consciousness.

He made his way over to the bed, feeling the cool air of the lair passing over his skin. He’d shucked his clothes off into a pile before he and Raph had crashed last night and hadn’t bothered to put them back on, despite the chill. Something about being nude near Raph just felt right.

The bed sagged even more as Casey lowered himself onto it, sitting beside Raph as he reached out and began to trace a finger over the turtle’s thick, muscular arm. Up and down he went, across the inside of his scaly upper deltoid and all the way down to his palm, tracing the life lines and calluses there. 

“Aw man, you started without me!”

Casey flinched at the whispered words and whipped his head around to stare at the entrance of the room, a blush forming on his face as he realized who it was. 

Mikey was peeking his head around the door, a grin stretching across the younger turtle’s face as he opened it wider and walked in, his bulky form nearly silent as he crept closer to the bed. The turtle was naked, though as Casey noticed, there was no sign of any external genitals. Raph had mentioned Mikey and Donnie being different, but actually seeing it was something else.

To his credit, Casey kept his mouth shut for a moment rather than yelling at the turtle to leave, which was his first instinct. But he calmed himself down enough to take a breath and glared over at Mikey as he sat his considerable weight on the already tortured mattress. The giddy looking turtle sniffed the air a few times and nodded to himself.

“G’morning, bro!” Mikey whispered with a grin as he wagged his brow over at Casey, “You guys sounded like you had a pretty nice night.”

Even with their talk yesterday over dinner and Raph assuring him that things would be okay, he still found it, well, weird to have one of his closest friends being so… open with him. He knew it was just Mikey’s normal demeanor and that now, things would inevitably get sexual more often between him and the brothers. But it didn’t mean that there wasn’t still a learning curve for him to get around. 

“Y-yeah. We, uh, we had a really good time.” 

Mikey nodded pensively, “Mm, certainly smells like you did. Me and Donnie heard you guys all the way in my room! Good for you, bro. Raph’s been super pent up lately, so I’m really glad you and him finally hit it off. We’ve all been sayin’ it for years now, but I knew it would happen eventually.” 

He glanced over at Raph and spied his still throbbing erection between his thighs, the sheets damp slightly where it was leaking. Arching an eyebrow at Casey he cocked his head towards it.

“You wanna take care of that or can I?” 

Casey shifted on the bed, curling his fingers into the sheets, “I… that’s… that’s not a question I’ve ever woken up to before, Mikey.” 

Nodding again, Mikey giggled and whispered, “Well, I certainly have! But nah, I get that dude. S’all good. Raph isn’t really particular anyway, so I’ll just handle it if you wanna keep him busy up top.”

“M-Mikey, I didn’t really mean—” 

“Relaaaaax, dude. I got this. S’not like it’s the first time I’ve woken up Big Red with a BJ. Certainly won’t be the last.”

Mikey giggled softly as he leaned back and pulled the edge of the sheets up and tilted his head to look under them. He grinned widely and then flicked his eyes back towards Casey, giving him a sly wink before he threw the sheets over his shell, covering his upper half completely. 

His legs went up behind him and bent back and forth in the air as he got comfortable, and Casey noticed a flick of green skin from just beneath the edge of Mikey’s shell. It twitched and moved slightly, and then flicked up as he realized that it was a tail, about eight to ten inches long and moving excitedly as the younger turtle shifted under the sheets.

I never even knew they had tails...

Casey’s widening eyes trailed over the shifting mound of sheets as Mikey’s covered form moved towards Raph’s now bulging hard on. A soft moan sounded from Mikey as the outline of his head met the tip of Raph’s dick.

Curious, Casey reached down slowly and pulled the edge of the thin, slate grey sheet taut and up, revealing Mikey underneath. The turtle was swallowing Raph’s shaft entirely, seemingly deepthroating him with little effort. He bobbed his head back and forth passionately, slowly, until he flicked his eyes up, catching Casey’s. 

Without missing a beat, he pulled off the slickened shaft and Casey watched, stunned as the youngest turtle lapped over the flaring tip. A pulse and shudder ran up the length, and Mikey lapped at it as a spray of clear precum landed on his open mouth. 

He moaned happily and licked at the tip again, running a three-fingered hand tightly up and down the shaft. Slowly, he nuzzled his snout lower and lower until Casey saw him flick his tongue out and wrap it entirely around the thick base of Raph’s dick. 

Those tongues were incredible with their flexibility and length, and Casey was dying to find out exactly what they could do to him. But Mikey clearly wasn’t finished working on Raph and he looked up at Casey sensually. 

He moved lower to lap at Raph’s balls slowly before pulling away and resting his head on his brother’s lower plastron. He looked up at Casey once more and smirked, rubbing his hand up and down Raph’s shaft slowly.

“You’re missin’ out, my dude. Wouldn’t mind having more help down here.” 

Raph suddenly let out a moan of his own as he shifted his body slightly, pulling at the covers with one hand and letting the other roam forward until it hit Casey’s hip. His eyes fluttered for a moment as they opened and he blinked several times before he winced with pleasure, trying to sit up.

Instinctually, Casey reached out and put his hand on Raph’s chest, pushing down slightly as he heard Mikey’s enthusiastic sucking begin again. Raph gasped and turned to Casey with his eyes wide and desperate. He moaned and leaned back onto his pillow, reaching down and placing one hand on Mikey’s head through the sheets while he pulled Casey on top of his chest with the other. 

Being manhandled by a giant turtle wasn’t a surprise to Casey, but the feeling of straddling a plastron with his naked thighs as his lips were captured by Raph’s was certainly still new. And knowing what Mikey was doing behind him only added to the excitement. 

He sighed into Raph’s waiting kiss, wrapping his arms all the way around his thick neck, feeling the bulging muscles of his boyfriend’s arms curl tightly around him. They moaned into each other, Casey’s cock twitched as it grew hard, leaking onto the hard surface of Raph’s chest. 

Mikey must’ve been doing something magical to Raph’s dick because he groaned lewdly into Casey’s mouth, gasping and bucking several times in a row. Casey deepened their kiss, sliding his tongue over Raph’s much larger one, tasting his warmth and swiping over his lips. He bit the turtle’s bottom lip softly, flicking his eyes up to look as Raph locked onto his with a shudder. 

And then suddenly, Raph captured Casey’s mouth again with a crying gasp, thrusting hard upwards several times and moaning low and deep in his throat. Casey knew he’d cum and he rubbed his hips into Raph’s plastron, clenching his thighs around the turtle’s sides and feeling each rapid pulse beneath him. 

Casey could actually hear Mikey swallowing and gulping as he guzzled down Raph’s load. He knew that even the youngest turtle in their family was easily taking more than he himself had been able to the previous night. It was something he’d have to work on but, luckily, he liked a good challenge. 

Breathless now, Raph let his head fall onto the pillow as he came down from his high.

Casey leaned over him, trailing kissing over his cheeks and neck, licking at some of the sweat there and savoring the scene before him. He glanced behind and watched as Mikey’s face emerged from covers, still grinning and clearly extremely satisfied with his work. He licked his lips, swiping a small glob of cum from his snout.

“And that’s how you wake up the big guy. Lemme know if you want any pointers.” He stared longingly at the sight of the nude human spread out on his brother’s chest. 

“Man, you’re hairier than I thought! That stuff grows everywhere!” Mikey moved forward and looked in awe at the smaller man, reaching out with a hand before he pulled it back.

“Er, I don’t wanna do anything you’re not cool with. I may be gung ho with Raphie but I don’t wanna make you uncomfortable.” 

Casey looked down at Raph who was still breathing hard, his eyes closed and shifting rapidly under his lids. He glanced back at Mikey and shrugged.

“Why the hell not. We’re already naked in bed together.” 

“Awesome.” Mikey laughed as he moved forward and sat over Raph’s lap, spreading his own thighs to straddle the bigger turtle like Casey was. 

Casey huffed before he spun around on Raph’s plastron, now facing Mikey and seeing the younger turtle finally laid bare before him. The difference between Raph and Mikey’s dicks was stark. Where Raph’s was much like a human’s in both placement and appearance, Mikey’s was… well, “more turtley”, as Raph had said. 

The long, dark purple spire emerged from a slit-like opening in Mikey’s lower plastron that Casey hadn’t ever seen before. The shaft itself was slightly thinner than Raph’s and Leo’s but the head was much wider and a different shape entirely, almost like a spaded tip. It was also a bit shorter overall than his brothers, but still much more impressive than a human’s. And like Raph’s, the entire surface of the shaft was covered in a clear coat of some sort of natural lubricant. A crisscrossing of thin veins ran up and down the impressive length like a spiderweb and only added to the alien look of the shaft.

Mikey was blushing slightly and he laughed nervously, “Yeah, uh, sorry if this is a bit more than you bargained for. I-I get it if you don’t wanna—”

“Mikey.”

The turtle looked at Casey and winced. 

“Don’t worry. You’re not a monster, dude. You’re just different.” Casey said as he arched an eyebrow at his brother’s dick, “Exotic, I’d say.”

Mikey’s face lit up and he smiled at Casey with relief, who laughed and continued.

”But do you not have, uh… balls?” 

Mikey looked confused for a moment and then nodded quickly, “Hell yeah, I do! They’re just internal, is all. Tucked away and safe inside, unlike you and Leo and Raph. I think I got the better end of the genetic lottery myself.” 

Casey smiled back at him and nodded, “Well, if you’re used to Raph’s and Leo’s then you should feel right at home with mine.” 

“Dude.” Mikey’s eyes were suddenly set ablaze with desire as he leaned forward and tentatively sniffed at the human’s shaft. He stuck out his tongue and swiped across the leaking tip before he grinned up at Casey and, in one seamless dive, engulfed the entire length. 

Casey was shocked at the speed of the youngest turtle, suddenly unable to think straight as Mikey wrapped his wide turtle tongue around his length, creating an impossibly slick tunnel of warmth that glided up and down as he bobbed his head back and forth. Clearly, one of the benefits of being human was that the rest of your mutant ninja turtle family could do things with their massive tongues that just weren’t possible otherwise.

“Mikey, you’re amazing… Mmf!” 

Casey reached out and pulled Mikey’s bobbing head down, thrusting up into him with a gasp. 

Jesus, he’s been sucking for like ten seconds and I’m about to explode. 

Then from behind, a pair of arms wove their way around his waist and pulled him backward several inches. Casey glanced back and saw Raph’s hungry eyes again, only this time they were clearly fixated on his backside. 

With a pop, Mikey let Casey’s dick out of his maw, running his snout over it affectionately and smearing leaking pre and his own spittle over his face. 

He grabbed the base of the shaft and flicked his tongue over the tip before he asked, “Ever been rimmed before, Casey?”

Behind him, Casey watched as Raph leaned his face up against his lower back and then moaned as he felt that broad, sweeping tongue lap over his tailbone. He shuddered and shook his head. 

“Mmm…” Mikey gave a knowing smile and licked lower, lancing at Casey’s balls with his tongue as he pumped the human’s shaft, “Well, I won’t lie: we all kinda have a thing for it. Bit of a shared kink of ours that we all get off on doing. But man, Raphie is always just so… enthusiastic when he does it.”

Casey felt Raph’s tongue slide lower, flicking over the beginning of his crack. With just a few swipes, he already knew he wasn’t going to last long. The sheer sensation of his best friend licking him back there was miles beyond anything he’d been anticipating waking up to today. 

Slowly, the turtle beneath him reached and pulled him back more and more until he was sitting over his snout. Raph’s fingers pried his cheeks apart and Casey felt more vulnerable than he ever had before. Then the big turtle leaned forward and licked a stripe up his ass, gliding his tongue over the hot, musky hole of his human boyfriend. 

Casey actually jumped at the feeling and Raph did it again and again, driving that sensation right into the pit of his stomach. Mikey shuffled forward and then instantly engulfed Casey’s cock once more, eager to finish what he’d started as Raph worked on the other end. 

Then suddenly, Raph speared his tongue directly into Casey’s winking hole, drawing a cry from the human on top of him. 

It felt like a finger had breached him, only it was warm, slick, and perfectly malleable. It punched past his rim and wiggled it’s way deeper and wider, stretching Casey out. Raph’s tongue was finding all of the right spots until—

“Oh fuuuck !!”

That incredible bundle of nerves was struck over and over by Raph’s tongue, the tip plunging in and out repeatedly as the turtle expertly pumped against his lover's nub. It was like the fullness in his ass belonged there, and always had. It filled him up and he shuddered and quaked as he was rimmed by his boyfriend, and blown by his brother. 

Finally, he’d had too much. The dam had been nearing it’s limit since he’d woken up and now it was utterly spilling over. He cried out, jerking his hips back and forth, needing Mikey to swallow and Raph to eat him out deeper.

He came hard, feeling the pulses of his orgasm hit like a sledgehammer as he released jets of cum into Mikey’s mouth. Casey was already gasping as he ground his ass on Raph’s face, feeling his lover still eagerly inside him as he rode out his pleasure. 

Since he’d broken up with April, he’d only ever jerked off alone in the mornings, and even when they were together, this sort of debauched wake-up routine rarely happened, if ever. 

But now? Now he knew he could look forward to this whenever he wanted. Having four mutant turtles at his disposal? There couldn’t be anything better than that.

His orgasmic high finally began to drop off and his balls had been emptied. Mikey pulled off his dick, letting a few small spurts of cum land on his tongue and snout as he moaned in satisfaction.

Casey peered down at a sight he’d never even imagined before: a mutant turtle happily covered in a human’s cum, looking up at him lovingly. He shuddered again, Raph’s tongue still lodged inside him and pulsing against that nub of pleasure.

Mikey leaned forward and stuck his impressive tongue out like a dog, a few drops of Casey’s cum dropping onto Raph’s still hard member throbbing between them. He reached down and rubbed the drops into the musky, green skin as he looked up at Casey and winked. 

“Mmm. You taste pretty good, dude.”

He leaned forward suddenly and captured Casey’s mouth in his, sliding the remaining cum into the human’s mouth, toying with his smaller tongue as he did. 

Surprised at the sheer lewdness, Casey accepted the kiss. Mikey was endlessly passionate and it seemed his lovemaking wasn’t any different. He’d need to get used to tasting his own cum but… it honestly wasn’t that bad. He’d tried it before but something about Mikey feeding it back to him was incredibly hot.

He gasped as Raph’s tongue punched against his prostate again, the warping muscle slithering inside him as Mikey pulled back, tilting his head to look around Casey’s back. 

“You havin’ fun, Raphie?”

Casey felt a rumbling affirmation and then a slow, methodical retraction of Raph’s tongue. He gasped as it pulled out of his hole in all the best ways. Finally it was out, his ass open and slightly gaping, feeling like it had been stretched more than he’d ever managed on his own. 

Panting, Raph laid his head back on his pillow and moaned contentedly. He placed one hand behind his head and the other cupped Casey’s slightly flushed backside as he smirked.

“You two certainly know how to wake a guy up.”

Casey and Mikey laughed and nodded, all three of them buzzing with ebbing pleasure in the heat of the room. It smelled of a combination of sweat, heavy musk, release, and passion as they disentangled themselves from each other.

Mikey moaned with a slight stretch before he stood up from his brother’s bed and started walking towards the door. Casey spied his still throbbing, impressive purple member as he turned to walk away, his tail flicking this way and that.

“Hey uh… don’t you want someone to take care of that for you, Mikey?”

With a smile, Mikey turned back and shook his head, “Nah, I got Leo and Donnie waiting for me. Though by now, I’m sure they wanna start training.”

He grabbed his shaft and pumped it a few times with a knowing look.

“Guess I’ll just have to make it a quickie in the shower.” 

Raph rolled his eyes and spoke, “Mike, you know ‘quickie’ isn’t in our vocabulary. Leo’s prolly got Donnie all worked up and waitin’ for you already.” 

Winking, he turned around and headed for the door, waving his hand lazily in a goodbye as he added, “Oh, then feel free to join us, you two.”

Casey collapsed onto the bed with a big sigh as Mikey left, curling himself up next to Raph’s enormous form as the big turtle shifted onto his side. He rather enjoyed being the little spoon to such a truly massive one. 

Raph’s warmth was surrounding him so perfectly and Casey couldn’t help but snuggle into it with a contented sigh. He felt an arm slide over him and pull him close, the turtle nuzzling the top of his head with his snout. 

“You guys… do that a lot?” Casey asked. 

Raph mumbled into Casey’s hair, “Its a bit of a shock, I know, but… yeah, we have sex a lot . Like, constantly. I’m not kidding, we fuck more than rabbits. Donnie said it’s a combo of turtle’s natural mating season and the mutagen basically overchargin’ it. Ever since we were teenagers, we get pretty fuckin’ randy all the time.”

He reached down and pulled his dick slightly, rubbing it against Casey’s back with a chuckle.

“And just like our healin’, we uh, well, we recover real quick, as you can feel.”

“Dude, I’m not gonna be able to keep up with you , let alone three other turtles.” Casey arched his back slightly as he felt Raph pulse against him. He moaned softly and turned to face Raph, staring up at the big turtle in front of him as he arched an eyebrow.

“Was that true about you guys lovin’ to eat ass? That’s oddly specific for all of you to enjoy it so much.”

Raph blushed hard at the question and chuckled nervously as he answered.

“It’s a scent thing. That’s where it’s usually strongest on us, all that… heat ‘n musk. Drives our instincts to breed, at least it does for me. It’s also just hot, man. I dunno why. But we all love it. S’like a drug to me.”

Casey could clearly remember the feeling of being filled from that end, his ass still aching pleasurably from Raph’s tongue and he nodded. 

“I definitely get it. Not complain’ at all… babe.”

Raph smirked, “Hey, I thought that was cheesy?”

“Changed my mind. Plus I like the face you made just now, so I think I’ll keep it up.”

“I got somethin’ else you can help keep up.”

“Jesus dude, you’re impossible.”

“Mmhmm. Better get used to it, Jones.”

Casey grinned, “With pleasure. But I think you need to get cleaned up before training. So maybe hold off on round two until after.”

He paused and added, “Also… you guys have tails?”

Raph snorted and nodded, “Yeah, we got tails.”

“Well, I didn’t know that. Never seen you guys naked before so it was a bit of a shock.” 

“Well,” Raph sighed as he rubbed Casey’s hairy stomach, “We jus’ normally keep ‘em tucked away. They’re vulnerable in a fight and shit, which is why we all wear pants on the surface.” 

“Mmm vulnerable?” Casey asked, “As in…?”

“As in they’re really fuckin’ sensitive, you dick.” Raph laughed and leaned in to kiss Casey’s neck softly.

Casey arched his neck to give Raph more access, “Mm, noted. Turtle tails are extremely sensitive. I promise I won’t use that to utterly undo you the next time we have sex.” 

“The next time we have sex might be a week from now if you don’t let me out of my bed. C’mon.” Raph swiped his tongue over Casey’s neck once more before he sat up, pulling the human with him and sliding his enormous legs off the edge of the bed.

“Y’know how Leo is about bein’ on time for training. Wouldn’t put it past him to be a massive cockblock just for missin’ one minute of one session.” 

Casey groaned and stood up slowly, stretching out as he felt Raph stand up behind him, pressing his plastron into his slightly hairy back. 

“Guess you’re right. Maybe I’ll have to talk to Leo about giving you a morning off every once in a while.” 

Raph gave a half-hearted laugh, “I doubt that’ll work but y’never know. Leo seems to have a thing for you too. Though he’s got a thing for all of us, so it’s hard to say.”

Casey smiled doubtfully, “Uh-huh. Leo’s definitely got a thing for me.”

“He does. We can all smell it, dude.” Raph shrugged as he stood up and stretched out, groaning softly as his joints popped, “S’not my fault you can’t notice the obvious.”

“Mm, well, maybe you can let me know exactly what it is in the air around here that seems to make me such a hot commodity all of a sudden.” 

“You’re newly out and willin’, bro. Can’t help it if we’re all sex-crazed mutants with no boundaries.” Raph chuckled as he strode towards the door, trailing his hand down Casey’s shoulders until he grabbed the human’s hand in his. He pulled the smaller man along with him. 

“C’mon. Got a feelin’ we need to get a bit dirtier before we can get cleaned up.”


------


Steam was rolling out of the entrance to the showers as Casey and Raph approached, still completely naked and both of them unashamedly walking through the lair. Splinter was still in his room but Casey doubted he’d care if he saw any of them in the nude. From what Raph had said, the older rat seemed to be less interested in the fact that his sons were openly having sex with each other than the fact that it seemed to make them a better team. 

Still though, that same openness was wild to Casey. The atmosphere of the lair had taken on an entirely new dynamic, one that he was quickly working his way up to enjoying. 

As they rounded the corner Casey could hear several steady streams of water going in the room beyond. They walked through the large tiled area littered with random bits of clothing strewn over the wide wooden benches Donnie and Mikey had fashioned. It was a mainly a room for them to strip down in, but over the years, Donnie had worked hard to turn it into both a steam room and massage station, with the benches quickly able to be converted into stands and movable carts to work out the various muscles, cramps, and other issues the ninja turtles’ bodies encountered after training and fights. 

Beyond the room were the showers and Casey eagerly followed Raph into the thick haze of steam flowing out of the expansive space. The space was wide and tall enough to fit all four of the turtles with more than enough room to spare for Casey. It was expertly tiled and grouted, thanks to Leo’s precision craftsmanship and Donnie’s careful planning. On the floor between each of the shower heads were molded seats the turtles could sit in to have their shells and plastrons scrubbed clean. 

Two of the shower heads were going at full blast, both of them angled towards each other to create a cross-stream of hot water. Donnie was sitting in one of the seats facing towards the entrance as Mikey scrubbed at his thick shell with a coarse brush, and Leo kneeled in front of him, scrubbing at his plastron with one hand as he leaned down to kiss the inside of the nerdy turtles’ thigh. 

Donnie had his eyes closed and was moaning slightly as Casey and Raph walked into the room. The human stared openly at the three turtles while Raph reached over to turn on the third shower head, the hot water instantly shooting out and soaking his front. 

Mikey leaned over Donnie’s shell and kissed at his neck while Leo gave a swipe of his tongue against his brother’s thigh and then glanced over at Raph and Casey. He smirked at the two of them as he turned slightly and laid his head on Donnie’s thigh.

“Mmm, you two finally decided to get out of bed.”

Casey stood transfixed at the sight of Leo on his knees in front of Donnie. The nerdy turtle’s purple cock was long, hard, and throbbing as it rested on Leo’s shoulder, who had one of his hands wrapped around its base and was gently rubbing it up and down. 

Mikey moaned softly as he placed his brush on the side of the seat and turned, standing up straight and reaching down to grab his own cock. He pumped himself a few times before he laid his own purple shaft on Donnie’s shoulder, letting it slide slickly over his wet, scaly skin, the flared tip coming to rest just to the right of his brother’s snout.

Raph rolled his eyes and shook his head as he grabbed Casey by the shoulder and pulled him into the stream of water, causing the human to sputter slightly and recoil at the searing heat. The massive turtle started to run his hands up and down his own muscular arms, and Casey followed suit after a few seconds, his eyes trailing over Raph’s green skin. It seemed to take on an almost entirely new texture as the water flowed over his scales, slickening the skin and deepening the various hues of green. 

He let the wide stream of water run down his skin and hair for a few seconds before he rubbed his chest and stomach, a thrill going through him as it clicked that he was showering with the turtles, on display to them just like they were for him.

Leo moaned as his icy blue eyes surveyed Raph and Casey’s bodies, practically drinking them up. He rubbed Donnie’s shaft eagerly as he spoke.

“Well, we’re about done anyway. Just need to take care of Donnie and Mikey here. You wanna help, Raphie? I’m sure Casey would love to watch you work.”

Leo’s voice was almost teasing, and he enjoyed calling Raph out like this in front of his entire family. Though Casey could hardly blame him with the sheer amount of steamy, pheromone-laden air that was swirling around them. Even his human nose could pick up the heady, masculine scents. And although he didn’t react as strongly to them, he knew they were driving each of the turtles deeper and deeper into a lusty haze. 

Donnie moaned this time, clearly unhappy with being ignored for so long. 

“Guys, I really don’t care who sucks me off but this is ridiculous. Raphie, come over here and help Leo out. Casey… mmm, just enjoy the view. Or join in.”

Donnie stared over at Casey for a few seconds before he turned to his right and opened his mouth, letting his tongue hang out while he inched towards Mikey’s waiting cock. The flared tip easily slid into Donnie’s snout causing Mikey to shudder. 

“Shell dude, you’ve got the best mouth, I swear.”

Donnie simply swallowed more and more of Mikey’s cock, reaching around the younger turtle and pulling him close with a free hand. The other was positioned on Leo’s head and pulled him down further towards his crotch, which the oldest turtle seemed eager to allow. He leaned into Donnie’s lap and placed both hands on the undersides of his brother’s thighs and hoisted them up against his plastron. 

Casey and Raph watched as Leo spread Donnie’s legs in the air and leaned in, licking a long stripe over the turtle’s hole with his prodigious tongue before he pressed his snout tight against it. Donnie cried out and shuddered, letting Mikey’s cock drop from his mouth, strands of precum and spittle dripping off of the flared tip. 

Donnie was usually the most put-together turtle of the four of them. He hardly ever lost his temper or showed too many signs of emotional vulnerability. But Casey simply couldn’t look away at just how far gone the tall, leaner turtle looked as he was eaten out by his big brother. His tongue was hanging out of his mouth as he panted heavily, Mikey‘s dick still dripping next to him like it was waiting to be sucked.

In front of him, Casey noticed Raph getting hard again and he couldn’t help but reach out and run his slick hand over the green skin of his thick shaft. His boyfriend grunted and looked down at him, eyeing the hand on his dick before he spoke.

“Mind if I take care of Donnie for a minute?”

Casey glanced over at the three turtles next to them and then back to Raph.

“Is this what every morning’s like around here?”

Mikey giggled across from them, wagging his dick eagerly in front of Donnie’s snout, “Pretty much, dude.”

Raph grinned and shrugged, “He’s not wrong.”

Casey chuckled and nodded, giving Raph’s green cock one last squeeze before he turned and stepped towards the threesome beside them.

“Well, I might as well start being a productive member of the family then.”

Carefully, Casey stepped forward and moved next to Donnie, eyeing his leaking, purple dick as the crossing streams of hot water showered down on his broad, hairy back. He knelt down next to the sitting turtle, running his hand down his slick plastron as he turned his gaze upwards. 

The lean turtle was still gasping as Leo’s tongue plunged into his hole, and the sounds that were coming from between his thighs were lewd beyond belief. But Casey simply looked up at his new brother and tilted his head in a question. Donnie looked down at him and shuddered for a moment. 

“N-never thought you’d be in this situation, did you, Jones?” Donnie’s tone was almost playful which was a new experience for Casey. The usually stoic turtle was quickly coming undone right before him. 

“Nah, man.” Casey said softly as he leaned forward and placed a tentative kiss on Donnie’s taut thigh, and then reached out with one hand and grabbed the tip of his flaring penis, rubbing his thumb over the gaping slit that was pouring copious amounts of slick, clear fluid from it. 

“But I’m more than happy to be, uh, helping out,” Casey said as he pulled the impressive length towards him and flicked his tongue out. 

The taste was very similar to Raph’s, but the texture of the tip and purple skin was somehow smoother and slicker. Maybe it was something to do with the fact that Donnie and Mikey were more turtle-like than their brothers—either way, Casey instantly dove in for more, wrapping his lips as far as he could around the wide tip, drawing more moans from Donnie. 

“Dudes, I think we’re gonna be late for practice,” Mikey sighed as he felt Donnie turn and suck his shaft down again. He thrust gently forward and placed his hand on his brother’s shoulder as he angled himself just right to slide further down the other turtle’s throat. 

Leo pulled away from Donnie’s hole for a moment, breathing heavily as he stared up at the three others in front of him, his eyes glazed over with lust as steam flowed around them all. 

“Practice… can wait, little brother,” Leo said with a heavy breath before he turned towards Raph and stared expectantly at the towering turtle, “Well? You want in?”

Raph’s gaze was locked onto Casey as his boyfriend licked and sucked Donnie’s dick as best he could. It really was wild to him just how eager the human was to join them, but he couldn’t dwell on it long because the lusty haze swirling around them was getting to him. Leo’s words caused his dick to twitch and spurt slightly. He needed to be with his brothers. 

The muscled turtle shivered and moved towards Leo quickly, kneeling down next to him and breathing in deeply. His eyes closed and he moaned deeply as Leo slid his arms around him and pulled them together for a searing kiss. He could taste Donnie’s musk on Leo’s tongue and he gasped loudly as their throbbing turtlehoods pulsed and frotted against one another. 

Leo kissed him deeply, savoring the taste of his brother and the feel of their tongues sliding against one another. He truly loved this, his family and what they had. These moments were second to none, and every moment he got to experience them was perfection. But today was different. He eyed Casey slurping over Donnie’s tip and he pulled back from Raph, swiping a lick over his snout before he pulled the bigger turtle towards Donnie’s hole. 

Raph groaned with a shiver as Leo guided him between Donnie’s thighs and pushed his snout right into his brother’s already slick hole. Always eager, Raph slid his tongue easily into the waiting orifice and went to work, wrapping his arms around Donnie’s thighs and pulling him closer as he ate him out. The nerdy turtle’s tail was flicking rapidly back and forth under Raph’s ministrations, clearly happy with the treatment it was receiving.

Leo rose, standing at his full height of just over seven feet as he stared down at his family, his gaze lingering on Casey’s nude form. The human was tiny compared to their massive frames, but that offered up its own interesting solution to possible… positions. 

Casey was so preoccupied with the task of sucking Donnie’s dick that Leo’s movements underneath him didn’t register until he was bumped off of the purple shaft. The leader of the clan had maneuvered himself underneath Casey and suddenly lifted him up to where he was now sitting on top of his plastron, legs spread out on either side. 

“There we go,” Leo said with a sigh as he ran his hands over Casey’s ample chest, tracing his wide fingers over the human’s pectorals and rubbing at his pert nipples, “I think that’s a better seat for you, on top of me. Gotta say, I like the view from down here.”

Leo winked at Casey as he trailed his fingers down lower, taking the human dick in his hands. He traced his fingers through the wet pubes and softly cradled Casey’s hefty sack as he murmured during his exploration.

The leader leaned up, stretching his neck as he pulled Casey down towards him to whisper in his ear.

“Can I suck you?”

Casey nodded enthusiastically, “Dude, you can do whatever you fuckin’ want to me. Go for it!”

Leo leaned more and kissed the human’s neck, slithering his tongue over the wet skin before he pulled back.

“Well, in that case…”

Casey gasped and arched his back as Leo took his cock in his snout and sucked hard, swirling his tongue around and under his aching shaft. The suction he was creating felt like it was actually drawing pleasure outward from his balls and even though he’d cummed recently, Casey could already feel another orgasm rapidly approaching. 

Situating himself more comfortably on the eldest turtle’s chest, he leaned forward and pulled Donnie’s dick towards him, hurriedly trying his best to wrap his lips around the incredibly wide flare. He braced himself against Donnie with one hand and wrapped the other around his wide shaft, rubbing up and down the slick skin as rapidly as he could. 

Donnie himself was clearly at his breaking point, as was evident by the insane amount of precum he was producing, and from the fact that Raph’s invading tongue felt tighter and tighter as his hole clenched around it. Donnie pulled Mikey more towards him, one of his wide fingers circling around the youngest turtle’s rim as he deepthroated him. The youngest brother’s hips snapped forward and Donnie felt himself losing control. 

Mikey leaned back and cried out with pleasure as he came hard down Donnie’s throat, feeling his load shooting down the tight gullet his brother had offered. He leaned back slightly, letting the other turtle pull off him as he shot the rest of his load over his snout, coating it nicely with thick, creamy jism. He stepped back as his load tapered off, letting the stream of water run down his body as he panted, watching the rest of his family reach their peaks. 

Raph and Leo seemed to be on similar timers, both of them moaning and shuddering more and more. Raph suddenly stood up, panting and grunting as he rapidly jerked himself off with a cry, spraying his impressive load over Donnie’s front. Globs of turtle cum landed over Donnie’s plastron and his dick, and covered Casey’s face as he continued to suck on the nerdy turtle with gusto. 

Leo’s climax was just as swift and impressive, his own cock launching volley after volley of his thick, creamy cum onto Casey’s back and even catching Donnie’s snout, mixing with Mikey’s seed. He continued to suck hard on Casey’s dick as he came, moaning softly with unbroken pleasure as he felt the human come undone on top of him. 

Casey was sprayed down with so much cum that it felt like the showerhead itself was producing the stuff. The warm streaks and droplets landed on him as he felt Donnie’s flare widen even more and then pushed past his lips. He gagged suddenly, unable to easily accept such a large head but trying his best to accommodate. 

The human managed to suppress his gag reflex enough to hold the cock in his maw as he felt a gush of cum blast out of it and right down his throat. His eyes teared up and he wanted so badly to let go, but at the same time, part of him wanted to show the rest of the turtles that he was one of them. He could take this, just like they could. And that resolve was enough for him to withstand Donnie’s onslaught of an orgasm, filling his stomach with blast after blast of thick slurry.

Finally, he pulled off Donnie with some discomfort, letting the flared tip past his lips as he gasped and coughed, tasting that same delicious taste he had last night. As he coughed, he felt Leo’s finger push up against his hole just enough to add a slight pressure on his prostate, and he came hard. Though compared to the turtles, his orgasm seemed tiny. Leo eagerly sucked him to the last drop and held his softening cock in his mouth, the warmth feeling impossibly good as he came down from his high. 

Slowly, his senses started to come back to him and he glanced around the room, eyes half-lidded and body worn out from so much work. Raph was kneeling between Donnie’s legs again, licking softly at the base of Donnie’s retracting cock as he smeared globs of his cum over his brother’s twitching hole. They caught each other’s gaze and Raph looked so warmly and lovingly at Casey. He leaned forward and caught his boyfriend’s lips for a quick kiss, before returning to his work of cleaning up his brother. 

Mikey took a step closer to them all and leaned in to kiss and nip at Donnie’s bared neck, the other turtle absolutely spent and still gasping for breath. Mikey giggled as he kissed his way up to Donnie’s lips and the two shared a soft, intimate moment together before Mikey slipped a finger along his brother’s snout. He trailed it through the lines of cum that streaked across Donnie’s face, gathering it up on his wide fingers before he slid one into his mouth, moaning softly. He kissed Donnie again, sharing the warm mixture with his brother as Casey watched, transfixed. 

Donnie pulled away from Mikey and looked over at Casey, his half-lidded eyes still filled with lust. He leaned forward slightly, drawing his finger around his snout and catching streams of Mikey and Leo’s cum on his tip before he reached over and held it in front of the human. 

“Wanna taste?” Donnie’s voice sounded almost dreamy, halfway between his intense afterglow and utter sexual exhaustion. 

Wordlessly, Casey leaned forward and lapped at Donnie’s thick finger, flicking his tongue and coating it with Mikey and Leo’s seed. It was utter debauchery and possibly the sluttiest thing Casey had ever willingly done but… it actually tasted amazing. And knowing that he’d now tasted each of the turtles sent a wild thrill through his body, like he’d passed some sort of unspoken qualification. 

Leo finally pulled off of Casey’s softening dick and sat up slightly, using the seat Donnie was on as a brace against his shell. He slid Casey down into his lap and the two stared at each other for a moment. The human was blushing profusely now, waves of heat and lust and embarrassment radiating off of him after what he’d just done. 

“T-thanks for, uh… all that , Leo.” 

Leo simply stared at him for a few more silent moments before he leaned in and captured Casey’s mouth with his, sliding his tongue against the human’s and wrapping his big arms around his tiny frame. 

Casey was taken aback at the tenderness Leo was giving off, but at the same time… Raph had said he’d had a thing for him. Maybe this was just his way of letting him know. 

Regardless, Casey returned the kiss with passion, sliding his smaller tongue against the turtle’s and enjoying the pleasant feel of Leo’s hands on his cum-slicked back. 

Finally, Leo pulled away and nipped at Casey’s neck, drawing a gasp from the human. 

“Mm… no problem. Wanted to do that last night but… well, last night was for you and Raph. Though I have to say, watching you two was more than enough for my needs.” 

Raph cleared his throat as he walked up to the two of them, hands on his hips. The look on his face was a mixture of jealousy, lust, and annoyance. 

“Mind if I clean off my boyfriend, Leo? You did jus’ get him all dirty again.” 

Leo looked up at Raph and nodded with a satisfied grin, “By all means. Though I think you also had something to do with that, Raphie.” 

Casey was pulled up with Leo as the leader stood, and he let his feet dangle for a moment before the taller turtle placed him back on the ground. 

Mikey was already rubbing Donnie down with a large, soapy sponge as Casey glanced back at them. Leo smirked and shook his head as he turned and reached over, grabbing another sponge from the side of the chair and dousing it with soap.

Raph sighed as he took Casey’s hand once again and pulled him off to the other running showerhead, letting the still steaming water pour over both of them. The big turtle rubbed his boyfriend up and down, getting most of the sticky residue off of his hairy skin. 

Casey moaned softly at the turtle’s touch, happy to let someone else wash him after exerting himself twice already this morning. But as Raph rubbed him down, Casey felt himself staring at the turtle in front of him, turning his gaze up to look at his face under the spray of water.

This new dynamic was incredibly hot. It was… unbelievable the changes that a single day could result in, and Casey couldn’t entirely wrap his head around just how easy it felt to switch into an entirely different role. They were all still fighters and defenders of their city. But now, among each other, they were family and, obviously, lovers. It wasn’t what Casey had ever expected or believed would happen. But now, having just utterly debauched themselves in front of each other (and enjoyed it immensely), Casey didn’t ever want to go back. He couldn’t go back. 

He wrapped his arms as best he could around Raph’s waist and hugged him tightly, feeling the pulse of his slightly more rapid heartbeat through the hardened skin of his plastron. Casey turned his head to the side and just held onto Raph until the larger turtle got the message, wrapping his muscular arms around the naked human as they both stood in the steaming spray of the water. They nuzzled into each other, Raph kissing the top of Casey’s head softly as they swayed slightly side to side.

Leo, Mikey, and Donnie looked over at the two of them and Casey hugged Raph tighter. 

This is what I’ve needed for so long. 

Finally.


------


“Mr. Jones, I wish to speak with you in my study.” 

The low, even voice carried across the dojo even with the sounds of weapons clashing against each other. Casey’s head whipped to the side as he clenched his waist and completed another hanging leg raise. He was out of breath and sweating profusely as he grabbed the damp towel hanging off the bar he was on, wiping it over his flushed chest and neck. 

He stared over at the diminutive figure of the rat across the dojo who was standing stock still at the entrance to his quarters. His four sons had stopped their training and followed Casey’s gaze, each one looking with a confused expression. 

“Uh, sure, Master Splinter.”

The old rat nodded slowly and turned, leaving the five of them behind as he walked out of sight. Casey grabbed the bar and bent backward, letting momentum take his body back and down before letting go and dropping to the padded floor. He wiped his still sweaty torso as best he could with the damp towel before he grabbed his grey tank top, pulling it on and walking towards Splinter’s door. 

“Someone’s in trouble.” Mickey snickered as he walked past the equally sweaty and exhausted turtles in the middle of the dojo. 

Raph grunted, “Shadup, Mikey. He’s fine. Splinter jus’ wants to talk about… everything that’s happened with us. S’all it is.”

Casey smiled as Raph nodded towards him, assuringly. He tossed his damp towel towards the towering turtle who snatched it out of the air with ease before bringing it to his nose to sniff. 

“Mm, nice an’ fresh.” 

“Keep it in your pants, Raph.” Leo said with an eye roll as he flicked his dulled training swords with a flourish, cracking his neck and bouncing on his wide feet, ready to continue.

“M’not even wearin’ pants.” Raph mumbled as he took up his ready stance opposite Leo, spinning his sais quickly. 

Technically, he was right. Each of the turtles always donned wraps around their arms, wrists, legs, and feet, along with custom leather loincloths Donnie had fashioned to allow them a full range of movement during training.  

Donnie just shook his head and shrugged at Casey as he passed, readying up with his Bo staff opposite Mikey’s lazily spinning nunchucks.

“Good luuuuuck.” Mikey whispered as Casey stepped up towards the sliding tatami door. The turtles immediately resumed their training, sharp breaths and hard hits of weapons once again filling the space.

Casey had only been in Splinter’s study one other time, back when they had defeated the Shredder. The old rat had bestowed them all with small gifts, and Casey still had his; a handwoven armband containing the Hamato family crest and words of strength written in Kanji. 

Looking around, not much had changed in the proceeding years as far as Casey could see. Small candles hung from a small but intricately made candelabra in the center of the room, giving a soft, warm glow. On the far wall, there were still stacks of books lining the walls, ancient-looking texts with thick spines and dusty pages that Casey had no doubt Splinter had read many times over, though where the rat had gotten them from, he had no idea.

To his left was a small wooden shrine standing in the corner. The wood was worn and old, but looked sturdy, like it had survived a lifetime with many more to go. Propped up on it’s plinth was a faded painting of two men and a girl, posing together. Each of them wore what looked like traditional Japanese garb, with more written text going over the right side. Beneath the painting stood three candles, two of which were lit. 

“Mr. Jones.” 

The voice was low and even, coming from Casey’s right. He stood and turned towards the source, finding Splinter kneeling on a small, padded mat before a low, wooden table. His long tail was curled around his petite, robed body.

The old rat looked at Casey for a moment longer and gestured towards the door.

“If you wouldn’t mind.”

“Oh, sure.” Casey reached to his side and pulled the slim, paper door closed behind him, the sounds of the dojo slightly dulled.

Splinter nodded in thanks and then looked expectantly towards him. 

Casey got the hint and walked up to the small table before kneeling down opposite Splinter, centering himself on another padded mat. He bent forward slightly in an attempt at an awkward bow, unsure of protocol. 

The rat chuckled softly, “Mr. Jones, please relax. I am not here to berate you or scold you. I merely wish to ask certain things of you, and it is my hope that you will answer truthfully and honestly.”

“Oh.” Casey said as a wave of relief washed over him, followed quickly by another wave of anxiety. “Uh, well, I’ll answer any questions you have, Master Splinter. No worries.”

“Mmm, that is good. Tea?” 

Casey's eyes were still adjusting to the dim light of the room and he realized that a small tea set had been placed on the table. The pot was a slate grey and simple, as were the set of small cups on either side. 

“Uh, sure, yeah, I’d love some.” Casey said, more wanting to appease the rat than to actually drink anything.

Carefully, Splinter lifted the teapot and poured a small amount into each of the cups, placing the pot back onto the pad at the center of the table before reaching down and grabbing the cup with his clawed hands. Casey followed suit, raising the cup up and waiting for Splinter to continue. 

The rat nodded and slowly tipped the cup back into his muzzle, taking a small sip. Casey did the same, letting the warm, honey-like liquid flow down his throat. Surprisingly, it was a delightful taste and he arched an eyebrow before taking another small sip. There were subtle hints of mint and honey as he closed his eyes and savored the flavors he could identify. 

“I am very glad you enjoy it.” Splinter said with a satisfied look on his face, nodding happily, “Only Leonardo and Michaelangelo seem to have a preference for this blend, and I do so enjoy making it.”

“Yeah, it’s… it’s really good.” Casey said as he took another sip and set the cup down on the table. 

“Mm… I find that tea helps to calm my spirit, especially during times of change and hardship. Though, I do also enjoy the taste itself. My mutation left me with a much wider range of taste compared to when I was a human.” 

Casey nodded, “Oh, I guess I hadn’t thought of that as having as big of an effect but… yeah, that makes sense. I’m sure you enjoy Mikey’s cooking even more than I do.”

The old rat nodded back, solemnly, “Mmm, many years ago, when Mikelangelo was starting to expand his interests, he would make many, many different recipes from books I found for him. Getting all of the correct ingredients was often impossible, but he always seemed to have a way of making the most extraordinary results out of the most basic of options.” 

Splinter had a far-off look in his eyes for a moment, like the memories were playing out right before his eyes. He gave a small sigh and shook his head slowly. 

“But now, I am an old man. My stomach often does not agree with me, despite my son’s accommodations. I find myself simply drinking tea and taking what nutrients I can from Donatello’s prescriptions.”

Casey nodded slowly, “I… noticed that more and more recently. You haven’t eaten much with us at the table.”

“Yes. It is an unfortunate reality that we all must face. I am… not young. And what my mutation has given me in skills and strength in my youth, it seems to have taken as much from my vitality and health in my old age.”

“I, uh… I know normal rats don’t have long lifespans.” Casey said uncomfortably, “But you were human before. That’s gotta mean--”

Splinter held up a hand, “Casey Jones, I am not nearly at death’s door quite yet.”

He chuckled to himself and sipped his tea, “I feel I have many, many years left in me still. I simply require more help than I used to, of which my sons are more than capable of providing to me.”

He paused, looking directly at Casey. 

“And of which, you are now included.”

Casey looked up from the table at the rat with wide eyes for a moment, locking onto his black, glassy ones. The candles flickered softly around the room as a few seconds passed. 

“I….”

Splinter waited patiently, blinking slowly as Casey gathered his thoughts.

“I’m… thank you, Master Splinter. That’s… that’s a really big honor a-and, and I don’t know if I’m exactly worthy of it but....” 

Splinter tapped the table with a clawed finger, “You are worthy, my son. You have helped protect our family’s secret existence since we have known you. And you are an exemplary defender of this city, as shown by your willingness to continue on, even after Shredder’s defeat.”

He flicked his whiskers in what Casey would’ve described as a hint of a smile as he continued.

“Ours is not an easy life. My sons have grown stronger, more capable, and more daring as they have matured. And you, a human, have grown along with them in that. You may not have all of the skills of a ninja, but you have the heart of a warrior. Courageous. Fearless.”

He paused and looked directly at Casey. 

“And loving.”

Casey’s face blushed softly under the series of compliments Splinter was showering him with. The rat was usually so stoic, so pensive. But it was a rare gift to have the turtle’s ninja master being so open and honest about his opinion. 

“My sons are…” The rat sighed as he glanced at the entrance, “They are everything to me. And you, Casey Jones, are… everything to Raphael. I have seen it growing in his eyes for years, and it is quite apparent when he is around you now. There is love between you two, and I am proud that he and you have finally begun to explore its possibilities.”

Casey looked down at the table, blushing still as he shifted on his padded seat. He rubbed his thumb and forefinger around the edge of the teacup, digging his nails into the lightly textured surface. 

“I have. We have.”

Splinter nodded again.

“And as you know, my sons are also everything to each other. In all the ways they can be.”

Looking up, Casey watched as Splinter placed his hands on his knees and sighed.

“Their love is one I fear the world may never be ready to accept. We are… uncommon in all the best and worst ways, as I was when I was human.” Splinter looked down for a moment, his eyes wandering over his clawed hands. “But you have accepted it, Casey Jones. Leonardo informed me of your conversation during dinner last night.” 

Splinter looked up and stared at Casey with an intensity and a curiosity that he felt bore into his soul. “I must ask you: why?”

Casey smiled and looked away, leaning back slightly as he scratched the back of his neck.

“Master Splinter… the world’s been going insane these past few years. Pretty much ever since I met you guys, I’ve been dealing with the repercussions. Of knowin’ that mutants live under New York. That ninjas and robots and aliens have been fightin’ for control of Earth. And I’ve fought with you guys, every time, no matter what.”

Looking back at the rat, he continued, “I dunno what it says about me, but Raph has been the closest person I’ve had in my life. And Leo, Mikey, Donnie—they’re my brothers. I’d die for all of them if it came down to it. An’ when I… realized I… loved Raph, more than just a best friend, it scared the shit outta me. Er, sorry—”

Splinter held up a hand, “Speak freely. I am not some brittle-eared priest.”

Casey laughed and nodded, “You’re definitely not, Master Splinter.”

“But yeah, I got scared.” He continued, slowly at first but rapidly picking up speed, “I’ve had dreams, some good, some bad—but all about what I was strugglin’ with. For the past few years, ever since April left, I’ve been dealin’ with all this shit alone. Keepin’ it bottled up. And it just got to a point where I… I wanted to tell Raph, not because I was tired of holdin’ it all in, but because I felt like I was lying to him. And the relief that came with tellin’ him was… it was amazin’. And then to have him not only accept me, but to tell me he felt the same way, I—”

Casey glanced at Splinter who’s black eyes seemed to be glistening slightly. There was no way he was getting emotional… right?

“I know you’re worried about your sons. And about me. But I also know that you know what Raph and I have is real. And that I care so much about him, and… our family. I would never hurt any of them intentionally. And I know that this is finally where I belong, Master Splinter.”

The old rat looked at the human across from him for a long time, completely silent. Casey stared back at him, waiting. 

“This is where you belong, my son,” he said finally, nodded sagely, “You are part of this family, and you have my blessing.”

Casey’s shoulders dropped with tension he hadn’t realized he’d been holding. Letting out a sigh, he nodded in return.

“Thank you, Master Splinter. I’m… I’m honored.” 

“As am I, Casey.” 

Warmth bloomed in Casey’s chest as the two of them sat quietly, letting the emotions of the conversation roll over them before Splinter cleared his throat. 

“Now, what is this that Donatello has told me about? An experiment with mutagen?”

“Ah,” Casey said with a pause, “Yes. I—er, well, I was planning on being his guinea pig later today. He’s testin’ a way to make humans immune to the mutagen the Kraang have been using, the same stuff that mutated all of you. If it works, he’ll be able to have a big advantage against whatever the Kraang are plannin’ next.”

He hesitated as he bit his lip, “But… he needs to test it out on a human first. Make sure the bugs are worked out. That’s the risk.”

“Mm, so you are willing to risk your humanity for this?” Splinter asked pointedly.

Casey shrugged, “Well, technically, Donnie has a small amount of retromutagen left over. If anything goes wrong, he can use that to… unmutate me. But yeah, I mean, I’m willin’ to do it. We’ve been fighting the Kraang for so long, and it’ll be nice to have the advantage for once.”

Splinter closed his eyes and sighed, “Leonardo and Donatello have explained as much to me, but I wanted to hear it from you. I agree that this is an important step forward against an old enemy, and I know that no matter what happens, you will be in the best of hands. But I must advise caution, my son. This is something even Donatello cannot fully prepare for, despite what he may say. I want you to be certain in your choice.”

“I am certain, Master Splinter.” Casey said assuredly with a slight bow, “I understand the risk and I want to go through with it.”

Slowly, Splinter rose from his seat, standing over Casey from the opposite end of the table for a moment before he stepped to his right and walked slowly across the room. Casey shifted on the mat and watched as the rat went to the small shrine in the corner of the room and removed something from a drawer, grasping it in his hands as he made his way back to the table and sat down again. 

“If this is your choice, then I have a gift for you.”

“A year ago, Raphael came to me and spoke about his feelings towards you. What you meant to him, and how he felt. He… made this for you but gave it to me for safekeeping, until the time was right. And I believe it is.”

Splinter held out his hands and Casey reached out his own, cupped together as the rat placed a softly wrapped item on them. He held his grizzled, clawed hands against Casey’s for a moment before pulling them away slowly. 

Casey looked down at the item and brought it closer to see in the dim light. Whatever it was, it was made of a soft, sturdy feeling fabric. He unrolled the bundle in his hands and stretched it out.

It was… a bandana. 

A black bandana like the ones the turtles always wore, only as Casey looked more closely, there was more than just black. Raph had woven in white alongside the black and as Casey held it up, he realized that it closely resembled the hockey mask that he always wore on their aboveground adventures. The bandana itself was much like Raph’s, meant to fully cover Casey’s head and with long tails that could easily be tied back, and eye holes cut out in the front. 

He flipped it over in his hands, a smile growing on his face as he felt his chest tighten.

As he turned it over, he noticed on the underside there was a series of Japanese character stitched onto the fabric: 愛した 

“What does this mean?”

Splinter smiled and simply said, “Loved.”

Casey’s eyes widened. 

Raph’s had it bad for me for this long… damn, I gotta make it up to him somehow.

He clutched the bandana in his hands as he looked over at Splinter, who was smiling across the table at him. 

“I… I don’t know what to say.”

Splinter stood up again, “I think, maybe on this occasion, it would be better to simply put it on and show Raphael. Turn around and let me assist you.”

Casey nodded and turned on the pad, facing the wall to his right as he placed the bandana on his head, pulling it down slightly to fit under his eyes and across his nose. The fit was loose until he felt the rat’s hands pulling at the tails of the cloth, knotting them together and pulling the entire thing slightly more taut as it nestled snugly around his skull.

After a moment, he felt Splinter’s hands leave the back of his head and he turned around to face the wizened rat. 

“Mmm.” Splinter nodded approvingly, “Casey Jones, my son. Welcome to the Hamato Clan.”

He bowed forward towards Casey, who returned the gesture. Splinter stepped forward and placed his hands on Casey’s shoulders as he remained bowed. With his deep, raspy voice, he recited:

“Anata ga shukufuku sare, ai sare, jinsei de osore wo shirazu ni iraremasu yōni.”

“What does that mean?” Casey asked as he straightened up from his bow. 

Splinter chuckled a bit, “Study up on your Japanese, my son. In this family, you will need to know it.”

“Oh great, more homework.” Casey grumbled, much to Splinter's satisfaction.

The rat continued to chuckle as he gestured for Casey to stand up. The two of them walked towards the entrance to the room. Splinter stood next to Casey, a foot shorter than him but still seemingly taller in presence than any of the turtles. Beyond the door came the slightly muffled sounds of the brothers’ continued training.

“Thank you again, Master Splinter.” Casey said with a glance to the rat at his side.

Splinter looked at him and smiled softly for a moment, before he reached and slid the slim door open, revealing the turtles, still engaged with each other in the dojo.

“Yame!” 

Splinter’s voice carried powerfully across the wide room, and all four of the turtles instantly stopped their fighting and turned towards the door where Splinter and Caseyemerged from. Each of them sheathed their weapons and lined up, kneeling on the mats and bowing their heads slightly. 

Stepping out, Casey stood next to Splinter, a few feet in front of the four hulking turtles.

“My sons, we have a new addition to our clan. One worthy of our name, our respect, and our lives—as we are worthy of his.”

Casey felt Splinter's hand on his back push him gently forward, and he stepped up slightly. The turtles, already bowed, bent forward until each of their heads were on the ground in the ultimate sign of respect. 

Splinter leaned forward slightly on his cane, looking down at his sons. 

“This is not a choice that I make lightly. The Hamato clan has been made up of the five of us for your entire lives. Only after conferring with each of you and meditating over many sessions do I feel that this is the best decision for our future. So now, I ask this of you all: Do you accept this human as your true brother?”

Their reply was instantaneous.

“Hai!”

“Do you vow to protect him with your lives?”

“Hai!”

“And will you swear to never abandon him, to be there for him in his times of need, and to share equally in his victories and his defeats, as he will share in yours?”

“Hai!”

“Then I present him to you now: Casey Jones, of the Hamato Clan. Rise and greet your new brother, my sons.”

What felt like a wall crashed into Casey as he opened his eyes, which had been tightly shut the whole time. It wasn’t that he was embarrassed—ok, maybe a little—but Casey was never one to make such a fuss about family stuff. Though maybe the fact that he’d had no family to officially call his own since he was a kid had something to do with that. Regardless, he opened his eyes to a wall of green muscles and tan plastrons surrounding and towering over him.

Warm arms wrapped around his entire body as Raph tucked him into the tightest bear hug he’d ever been in. The air felt like it was being squeezed out of him as Mikey, Leo, and Donnie joined in, laughter and warmth filling the air as his brothers piled on, toppling Raph’s significant frame over and causing a massive shudder in the big room. 

He couldn’t tell whose arms were clutching which part of him, but he could feel the love and adoration of his brothers coursing through him. Managing to lift his head up, he spied Raph looking down at him, his face close and his warm breath flowing over him. 

Casey leaned forward and kissed the big turtle softly, before letting out a big breath and a slight chuckle as he simply accepted the fact that he was stuck in this turtlepile until his brothers decided he’d had enough. 

Splinter watched as his sons reveled in Casey’s presence, clearly happy with what he had decided to do a long time ago. His sons were still youthful even in their more mature age; time had not dulled their emotions one bit, merely focusing and enhancing them. Adding a new member to their clan was not an easy decision to make, but he knew that Casey Jones would make them stronger than ever. The human would bring them all together in one way or another.

He placed his hands on the tip of his cane, smiling at his sons who, even if it was just for this fleeting moment, felt like kids again.


------


“So, no history of disease running in your family?”

Casey tapped his barefoot on the cool concrete of Donnie’s lab, arms crossed over his shirtless chest as he waited for the turtle to finish with his questions. He’d stripped down to his briefs, as per Donnie’s instructions, and though he wasn’t shy about his body, the anticipation combined with the coolness of the lab made him shiver.

“Not that I’m aware of.”

“Mm. Other than your ribs, any recently broken or damaged parts of your own body that I should be aware of?”

“Just my slowly draining sanity, Don.”

“Didn’t think you had any left.” The tall, lean turtle rolled his eyes as he tapped rapidly on his tablet, “No recent illnesses? Colds, the flu, a stomach bug?”

“Nope.” Casey sighed as he glanced over at Raph who shrugged his shoulders. 

The hulking turtle was leaning on the metal bars surrounding Donnie’s supercomputer, and standing next to him was Leo, looking over at Casey with wary eyes. Mikey was spinning around aimlessly in Donnie’s well-worn custom chair, kicking his feet up every so often. 

“Donnie, you’ve literally asked him like… a billion questions. I think he’s ready.” Mikey said, his voice pulsing with the force of the spinning chair. 

“Hardly. I’m not going to run an experiment like this without checking all the boxes, Mikey. This is highly volatile stuff we’re dealing with.” Donnie said as he continued to tap away at his tablet while circling Casey slowly, glancing up at him every so often and typing notes.

Finally, he stopped directly in front of Casey and put his tablet down with a sigh. He pushed his horn-rimmed glasses up the bridge of his nose and looked down at the human in front of him, mumbling to himself.

“Mm… screening is done. Oh. Forgot about that. No, the bilateral gene augmentation worked fine with the previous two tests of version four point one, but the new version tested just as well with half the reactionary effects to the cells…. Hm. I wonder if there’s any more room for improvement in the higher strand sequences of the next batch. Note to self.”

Nodding along to his own musings, Donnie seemed to be waiting for something to happen before he realized, as usual, that he was the smartest person in the room. 

“Oh. Right, so, Casey uh… get up on the table and I’ll get things started for you.”

Casey chuckled slightly as he laid himself out onto the padded table covered in a length of white medical paper. 

“Jesus, Don. You’re actin’ like you’ve never done this before.” 

“Hilarious, Casey.” Donnie said flatly, clearly trying his best to ignore just how wracked his nerves were. 

It wasn’t normal for him to feel so unprepared in situations like these. Despite his genius, he was seriously pushing the boundaries of both his own hypothesis and his abilities and skills in the laboratory with this experiment. 

“You got this, Don.” Leo walked up and placed a soothing hand on Don’s shoulder, who flinched slightly at the contact and then seemed to truly relax, at least for a moment. 

Raph walked up slowly to Casey’s side and stood over his new brother, taking his smaller hand in his and rubbing his larger thumb over the soft skin. 

“Nervous?” he whispered.

Casey glanced at Donnie as he fidgeted with various things on his workbench, and then looked back to Raph. 

“Yeah.” Casey let out a breath and squeezed the turtle’s hand. “Was worried you were gonna say ‘ Oh, Casey, baby, you’re so brave and I can’t bear to lose you. Saving all of humanity isn’t worth losing you !’”

Raph snorted at Casey’s mocking voice, “Damn, I must’ve given you the wrong impression that I was ever that sweet on you. Rest of humanity’s pretty important, ‘specially with the number of times we’ve had to save their shit. I might be willin’ to trade you for seven billion other people.”

“Ouch!” Casey said with mock hurt, clutching his chest like he’d been shot, “Emotionally wounded by my boyfriend before potentially dying on a slab in a sewer. Can’t think of a worse death than that.”

“Oh, I can think of several worse deaths than that .” Raph said as he leaned in close and softly nuzzled Casey’s cheek, giving it a kiss before he moved down and captured the human’s mouth with his.

Casey wrapped his arms around Raph’s neck and returned the kiss, tasting his turtle’ lover’s tongue on his own as he felt his loins stir slightly. A throat cleared next to him and he opened his eyes, glancing at an expectant looking Donnie and Leo, both of their arms crossed impatiently over their chests. 

Raph pulled back, hovering his snout next to Casey’s ear.

“Love you, Case’.” 

“Love you too, Raph.”

“Gross and lame,” Mikey said, exasperated from his perch in Donnie’s chair as he surveyed the room in front of him. 

Casey laughed as Raph stared daggers into Mikey from across the room while he walked towards him to wait for Donnie to start. Leo gave Donnie a kiss on his snout before walking up beside Raph and waiting once again. 

“Alright, let’s get started,” Donnie finally said, tapping his foot against the floor rapidly as he gathered up various vials and placed them in a row on his rolling table next to where Casey was laying. 

“First, I’m going to give you a precursor to the serum I’ve made. I’ve already tested both the precursor and the serum, individually and combined, on your blood from one of the samples you provided yesterday. Both reacted as expected, so I’m not anticipating any adverse effects in your system. Let me know if you feel anything after each injection.” Donnie’s whole body language seemed to shift as he fell into his usual medical pace and tone once again. 

“Put this monitor-band on your wrist for me.” 

Casey arched an eyebrow, “What, no leds and stickers stuck to my chest? No finger clamp thingy?”

Donnie snorted. “Those are so old-fashioned. This does everything they do and is more accurate.”

Casey pulled the wristband on and flexed his fingers. Instantly, a flood of information appeared on one of the monitors hanging on the wall next to him. Donnie glanced at it for a moment before nodding. 

“Alright, everything looks good. Ready?”

“Yeah, let’s do it.” Casey said, nodding as he glanced at Raph with a small smile.

“Okay, precursor is coming up,” Donnie said as he grabbed a syringe filled with clear liquid and walked to Casey’s side. He quickly swiped an alcohol pad over his upper arm several times, waiting for it to dry before continuing.

Carefully, he took Casey’s arm and turned it slightly, pinching the skin and quickly sticking the needle in before plunging the contents into the human’s body. Once the injection was finished, he removed the needle.

“Do I get to choose my bandaid?” Casey’s sarcasm carried well across the room, drawing a grin from Raph. 

Donnie rolled his eyes and held up a pad of gauze to the injection site. Mikey giggled slightly in the background.

“Pretty sure Leo has some Batman ones in the first-aid kit.” Raph said as he leaned into his brother, causing Leo to scowl.

“Okay, well, Batman’s clearly the best one you could have anyway. That’s not even up for debate.” Leo said with an annoyed look back at his brother.

Mikey shook his head, “Uh, Bats doesn’t even have healing powers, dude. Is he, like, gonna use a batarang to stop someone’s bleeding or something?”

The conversation continued in the background until Donnie checked the time after a minute, seemingly satisfied with the result of no result. He glanced down at Casey.

“Feel anything?” 

Casey shook his head, “Nah. Didn’t even feel the needle.”

“Good. By now, the precursor has circulated in your system and should have primed your body to accept the serum.” Donnie grabbed a larger syringe off of the rolling table. This one was filled with a more viscous liquid that had a golden tinge to it. He moved back to Casey’s side and swiped another alcohol pad over his arm. 

In a slightly higher spot, Donnie grabbed the skin of Casey’s arm and pinched, holding the needle just off of the surface as he looked down at him.

“Serum is going in. Ready?”

Casey swallowed and nodded.

“Yeah.”

His answer left an air of tension in the room, all of them knowing what was about to happen. Leo, Mikey, and Raph all leaned in and watched as Donnie slid the thicker needle into Casey’s arm and plunged the serum into him. 

Casey winced slightly at the punch of the larger needle and felt a slight burning sensation under his skin as the cool liquid of the serum met the warmer blood in his body. But Donnie was as quick as always and took just another second before he removed the needle and stepped back. 

For a moment, everyone held their breath as they waited for… anything to happen. Another full minute went by as Casey’s heart thumped more and more rapidly in his chest, and Donnie continuously glanced between his watch and the constantly updating information on the monitor from Casey’s wristband. 

Still nothing.

Donnie breathed a sigh of relief as another minute passed, his shoulders relaxing with the knowledge that at least for now, Casey’s body seemed to have accepted the serum. 

Soon, ten minutes had passed and Casey was starting to feel a bit more comfortable with everything. He nodded along with Donnie as the turtle explained the nuances of the serum he’d made. 

“Okay, this is good. I designed the serum to have a reaction rate similar to the mutagens, so it would’ve been obvious by now if your body had rejected it.” Donnie said as he checked over his tablet. 

“Er, and what would my body rejecting it have looked like?” 

Donnie tilted his head and thought for a moment. 

“Mm, most likely severe nausea, vomiting, along with hives and itchiness. Not pleasant, but also something easily fixed. Your body simply would’ve expelled the serum naturally after several days. But from what I can see, it’s bonded exactly as I had predicted to your cells. And like I said, since it has a rapid reaction, we can test it now, if you’re ready.” 

Casey felt his chest tighten at the thought of having raw mutagen come into contact with his body, and the monitor beeped as his heart rate spiked. Donnie looked closely at the monitor before he placed a hand on Casey’s hairy chest, rubbing it softly. 

“Hey, you’re alright. You’ve made it through the first half, and you’re in the home stretch now.”

He looked over at Raph who nodded and walked over to them, placing his own hand on Casey’s stomach. The two turtles gently rubbed his torso together, and Casey looked back and forth between them, trying to calm his nerves. 

Donnie smiled and Raph smirked as he trailed his hand down lower, letting his fingers graze Casey’s shaft through his briefs for just a moment. 

“Hey, don’t start something you don’t plan on finishing, big guy.” Casey said as he nudged his knee into Raph’s thigh. 

“I plan on finishing many, many times, believe me.” Raph replied with a wink before he backed away and let Donnie continue his work. 

Donnie tsked as he maneuvered around Raph, grabbed a stopped vial of purple mutagen and a small pipette. Once again, he stood beside Casey, glancing at his three brothers standing several feet away before he turned to face the human. 

“Moment of truth, part one.” Donnie whispered to himself. 

Then with a huff, he unstopped the vial and dipped the pipette into it, drawing up a small amount of the shimmering purple ooze. The stuff looked alien even from a distance. Up close, it looked like it was alive, with a constantly shifting hue that glowed from the inside. 

Donnie cleared his throat, “This is going to happen in two stages, provided we get past the first: simple skin contact. We know mutagen can infuse through a variety of skin layers in both humans and other lifeforms on Earth. But what I’ll be using is the upgraded mutagen we found in the Kraang facility, which is specifically tailored to human DNA. So, I’m going to drip a small amount on your chest. If it reacts… well, you’ll know. Even this tiny amount has enough kick to change a fully grown human into a mutant.”

He took a breath to steady himself and looked at Casey.

“Are you ready, Casey?”

Clenching his hands into fists and taking several deep breaths to try and steady himself, he finally nodded. 

“Go ahead, Don. I’m ready.”

Slowly, Donnie moved the pipette over Casey’s broad chest and lowered it until it was hovering just over his tan, hairy skin. Then, the turtle squeezed the rubber end, and the contents, equalling to about seven or eight drops of mutagen, squeezed out of the tip and fell onto Casey.

Casey, for all his anxiety, couldn’t look away. The purple ooze fell right onto him, each drop cold and shimmering as it landed on his skin, just above his stomach. It matted his chest hair down and globbed together thickly as the pipette emptied. And then…

Nothing happened. 

He stared at the ooze laying on him, certain that any second now, he was going to feel the burn of mutation, the pain of his body shifting into some unknown form. 

But nothing came. The ooze simply sat there and warmed to his temperature. 

He flicked his eyes to Donnie who was holding his tablet over his mouth, watching intently around Casey’s chest for any change. After a few moments, he shakily lowered his tablet and gulped, glancing over at the three turtles waiting with bated breath. 

“I… I think that counts as a success!” He turned and beamed at his brothers as they whooped and shouted in excitement. 

Mikey kicked his legs in the chair and stood, flipping off of the railing and sliding his arms around Leo and Raph as he hugged them tightly. All three of them were beaming now, but Raph was staring over at Casey like he was a marvel. Which, for right now, he truly was. 

Donnie adjusted his glasses slightly and reached down, sucking up the mutagen with his pipette again and placing it back into the vial. He rubbed Casey’s chest with a pad of gauze to clean it and disposed of it in a medical incinerator box off to the side. 

It was clear that the genius was thrilled with the result but he knew that the test wasn’t over quite yet. There was one last thing that needed to be completed before he could claim that it was a complete success. 

“Okay, time for the second part. This is the big one.” Donnie said as he readied the final syringe.

“To be completely sure that the mutagen won’t react to you, we need to test if it reacts to the blood circulating within your system. I’ll be injecting you with a large amount of the mutagen, just like I did with the serum. If it works, the serum will break down the mutagen and then your body will filter and expel it naturally, just like anything the human body has no use for.”

Casey nodded, appreciating the way Donnie was straightforward about what was going to happen. He just hoped that it did.

“Just this and then we’re all done, Casey. One last time: are you ready?”

Looking over at Raph who was still staring at him intently, Casey nodded slowly.

“Do it.”

Donnie readied the syringe and moved to Casey’s other arm, swabbing it with one final alcohol pad and then, with no hesitation, plunged it into the human’s arm. 

The mutagen swirled and glowed as it left the syringe and entered Casey’s body. This time, Casey felt a much more intense burning sensation shoot down his arm and he clenched his fist and grit his teeth. He shifted uncomfortably on the table as the burning sensation expanded from his arm to the rest of his body, the pain increasing slightly.

“Casey? Tell me how you’re feeling.”

Grimacing, he answered, “Ngh… burns. Like a shooting pain all over but it’s almost like it’s cold too. Aangh…”

The pain continued to burn away inside his veins, and he grabbed the side of the table with his other hand. A flop sweat broke out all over his body as he tensed. But then, after a minute of intensity, it seemed to finally start to ebb. 

Slowly, Casey could feel his tense muscles start to relax and he laid his head back slightly, breathing heavily inside and out. Donnie was immediately over him, wiping his face softly with a cool cloth and checking his numbers on the monitor which had lit up in red behind him for a moment. 

“I… I’m feeling okay now, Don. Seems like it’s fading.” Casey said as he took deep breaths in and out as steadily as he could. He closed his eyes and focused on calming himself down, hoping that they’d succeeded.

“This… this is very, very good news, Casey. We’re going to wait for a few more minutes just to be certain. As far as I know this… hasn’t even been done before, obviously, so I’m going to take this as slowly as I can. Raphie, Leo, Mikey, you guys can come over.”

Raph was there in a flash, kneeling next to Casey and holding his hand again. He brought it up to his snout and kissed it, softly nuzzling the back of it as he stared down at his boyfriend, clearly and utterly relieved. 

Casey smiled over at the massive turtle, his body feeling so much more exhausted than it had just a few moments ago. Now it seemed like he’d run a triathlon, and his muscles kept twitching slightly. But the pain and the burning was gone, replaced with a blissful coolness. 

Leo and Mikey knelt down next to Raph and placed their hands on him lovingly, rubbing back and forth as Casey looked at all of them in turn. 

“Not too bad for a guinea pig, eh?”

All of them smiled widely, even Don who knelt down on the other side of the table and placed his hand on Casey’s shoulder, rubbing it softly with his wide fingers. 

“Not bad at all, Casey. You did great.” 

A few more minutes passed and Donnie ran several more tests via the wristband Casey was wearing, collating as much new data as he could. He drew a few more blood samples from Casey as well, filling two vials of his blood to match with the other two he’d taken prior to starting the tests. 

After half an hour had passed, Donnie was ready to call it. 

“Well, despite the seemingly ever-growing odds that have been constantly stacked against us… I think we have a win for Team Turtle!” His voice had a tone to it that Casey had never heard before. It was joy, pride, and relief all wrapped into one and it suited the genius perfectly. 

“Fuck yeah!” Casey shouted from the table as he sat up, Raph’s hand gently helping him. 

All of the turtles shouted with joy, and Mikey went around high-threeing each of his brothers until he arrived at Casey, where he wrapped him up in a big hug and kissed him twice. 

Leo was beaming at Donnie and walked over to him, placing his hands alongside his snout and kissing him deeply before wrapping him in a hug of his own, which Donnie returned before pulling back slightly. 

“You should go tell Splinter. He’s still praying in his study, and he’ll want to know.”

Leo nodded and kissed his brother one more time before he turned around. Mikey stood up and, bubbly as ever, grabbed Leo’s arm.

“We’ll go tell him together! C’mon, Leo!” Mikey yanked his leader’s arm and pulled him towards the lab exit as quickly as he could force the bigger turtle to go. 

Casey watched the two leave the room and with a sigh, he swung his legs to the end of the table, letting them dangle slightly as he rubbed his chest and yawned. He really was tired now, and he just wanted to rest in bed with Raph by his side. 

Still tapping away on his tablet, Donnie asked, “You look exhausted, Case’. Are you thirsty at all? The reaction definitely took a lot out of you. Here, drink this.” 

He handed Casey a bottle of water from the medical fridge. Casey nodded thanks and opened it, downing the entire bottle in just a few seconds, amazed at how thirsty he was. The cool water rushed down his throat, pooling in his stomach and sending a slight chill through him. He handed the bottle to Raph who tossed it in the trash as he rubbed Casey’s back softly with his other hand, back and forth.

“Mm, yeah. I’m… just feeling like I got nothing left in the tank, Donnie. Really wiped me out.” Casey said, leaning back into Raph’s touch. He raised a hand to his head and scratched slightly at an itch there, moaning at the relief it brought. 

“Uh. Don.” Raph said quietly beside him. 

“Hm?” Donnie said, not looking up from his tablet. 

“Don!” Raph said with a bit more urgency as Casey scratched at his head, his eyes half-lidded. 

“What, Raph?” Donnie answered, annoyed, still not looking up from his screen. 

“Donatello!” 

That got his attention. He glanced up, wide-eyed at Raph in confusion. 

“What?”

Raph had his hand up off of Casey’s back and it was covered in… Casey’s thick, brown hair. Whole patches of it had fallen off of his skull and were landing in clumps as Casey continued to scratch. 

“Oh shit.” Donnie said as he put his tablet down and walked up to the table, causing Casey to shift out of his exhaustion for a moment and look up at the turtle. 

“What is it?” 

Donnie reached up and pulled Casey’s hand away from his head and ran a finger through the hair. As he did, everywhere he touched caused follicles to fall away and down Casey’s back. It was then that Casey realized something was wrong. 

“It’s… your hair. You’re losing your hair, Casey.” Donnie said as the rest of it completely sloughed off of the human’s head, leaving him bald. 

“Well fuck, I mean… is that like a side effect?!” Casey said, his voice instantly nervous as he shifted in his seat, turning around to see the clumps of hair behind him on the table. “Oh shit. That’s... that’s my fuckin’ hair, dude.” 

He reached up a hand and ran it over his head, feeling perfectly smooth skin there. He laughed, in spite of how weird it was, because of all the potential scenarios he’d thought of, leaving the experiment bald hadn’t been one of them. He shook his head and brought his hands back in front of him, before he realized something else was falling.

He glanced down and saw shorter, darker hairs piling on top of his hands. Instantly, he reached up and knew his head hair wasn’t where it was going to stop. 

Padding his face, he felt the thick patches of his once thick beard crumble off of his skin, and he reached up higher, feeling that his eyebrows were gone as well. As he looked down, it was like his barber had made an absolute mess of a simple trim. The small, shorter hairs seemed to be withering as they fell, losing their color and rapidly thinning out. 

Casey watched in awe and utter disbelief as his body hair followed suit, his once dense chest hair simply falling away and leaving his skin smooth and almost silky. A feeling of dread washed over him and he moved his hands over his body, wiping away the excess hair and letting it fall to the floor. 

“Donnie, what the fuck’s happening to him?” Raph asked, holding Casey steady, unsure of what to do. 

“I… I don’t know! This isn’t anything like what I’d anticipated.” Donnie said, watching closely while grabbing his tablet and checking his data. 

As Casey continued to rub his chest, feeling the bare skin under his fingers was surreal. He hadn’t felt this since before middle school when he’d gone through puberty. Gingerly, he rubbed his fingers across his skin, back and forth, marveling at the smoothness. 

But as he rubbed, he realized his fingers were getting harder to move, at least some of them. His fore and middle fingers seemed to want to move together, as did his pinkie and ring fingers. Holding them up, he watched as they twitched, trying his best to move them and feeling less and less like he had independent control. 

Suddenly, a dull ache ran through them and he stared dumbfounded as his fingers began to merge .

The skin warped and melded with an intense heat that sprouted seemingly from nowhere. 

It began in his left hand and he raised the other one, watching as they both mirrored one another, leaving him with six thick , wide fingers and a lot of questions. 

“H-holy shit, guys.” Casey said as he held up his hands, flexing his fingers into fists that looked… exactly like the other turtle’s. 

And then it hit him. That same heat flooded his entire system, blooming from his stomach outward and filling his entire body. There wasn’t pain yet, but the heat seemed to blind his nerves from any unpleasant transmission to his brain.

“Oh, fuck, oh fuuuck….” Casey groaned low in his throat, feeling his entire body tense beyond what had happened during the experiment. His muscles throbbed and he leaned forward on the table, a wave of intense, unexplainable sensations flowing over him. 

His muscles fired away, twitching under his smooth skin as he continued to groan and rock back and forth. 

As with his hands, his feet seemed to follow suit soon after. Casey’s toes began to merge, five becoming two large, wide digits complete with a single nail on each. And the changes flowed right up his legs. The muscles under his skin seemed to stretch and bulge, clenching hard and expanding as the skin began to darken from his usual tan shade to a decidedly more green one. The pigment was deep and pure, and it rushed up his legs and thighs.

As it ran up his legs, so too did his hands and arms begin to change. The same green color rushed from the tips of his new fingers down and up his bulging arms again. The muscles still shifted under his skin growing faster and faster as the color reached his shoulders. 

“Donnie, help him! You gotta do somethin’!” Raph yelled in a panic as Casey groaned again, his voice deepening and altering as the changes continued. 

“T-this shouldn’t be happening! I never… I… He...” Donnie’s words stumbled out of his mouth as he stood there, reduced to simply watching his friend mutate. 

“Nggghhhhaaaaaaahhh!” Casey moaned and let loose a yell as he writhed on the table.

As the green raced up his shoulders and thighs, it was then that Casey felt an intense pain, like a growing storm of hornets stinging inside his torso. He cried out again and leaned back into Raph’s hold, tears forming in his eyes and streaming down his cheeks as he felt himself growing larger. 

His spine expanded dramatically, lengthening and thickening along with his limbs and muscles. Arms, legs, even his neck—it felt like he was being pulled apart with hot chains and held together with solid glue at the same time, and he gasped at the deep shifting inside and out. His skin felt like it was bubbling and he moaned deeply, feeling his throat thrum with wider, larger vocal cords. 

Casey’s body flared even hotter, drawing a gasp from both him and Donnie as sweat broke out over his skin, the monitor on the wall flashing red. His back and front lit up and he threw his head back, shouting at the sudden rush of pain mixed with an almost unbelievable slow hardening of skin. It was toughening and weathering, like a leather hide that he was growing on the spot. On his back, his spine straightened and he felt a pulsing blast of heat and pain. 

His shoulders rounded and grew, enlarged to the point of matching Raph’s as he felt the skin bunch and harden more. As he writhed on the table, his torso started to segment, toughened plates growing out of his skin and puffing up, meeting the edge of the other plates and melding together. In his front, a plastron was clearly forming, covering his stomach and chest with its tan, impossibly hard layers while his muscles continued to grow and bunch underneath. 

And behind him, those same plates that had started to grow suddenly bulged outward, rounding along their edges and creating a hardened rim of shell. The texture and shape seemed to flow out of Casey’s back, his skin instantly bunching, hardening, and pushing outward to complete the half shelf just like the ones his brothers had.

His new plastron front and half shell back fused to his muscles and caused Casey to straighten up tightly, a web of nerves and connections weaving through his body and lighting up his brain with a cacophony of new sensations. 

Feeling his heart beating faster and faster, Casey brought a three-fingered hand up to his chest, pounding against his plastron as his internal organs began to shift inside. He could feel as each part of his body lit up with the mutation, organs growing and moving to accommodate different spaces. 

Groaning, he clutched his skull, bending forward, feeling the weight of his shell on his back as he did. His eyes teared up and his skin felt prickly as he moved his hands over the sides of his head. His ears rapidly shrank and dissolved into his smooth skin, leaving his head flush with his hairless flesh, save for two small holes that were soon hidden by a thin layer of skin. 

His nose cracked and snapped with a jolt, drawing more tears of agony, his sinuses suddenly aflame. Slowly, his face began to push forward, forming a slight snout. His nostrils pulled back into his skin, leaving two flared holes at the end of his snout. Teeth began to move and thicken, his gums shifting around and the taste of blood flowing over his tongue. Opening his mouth, he felt his tongue actually shift and thrust forward, thickening and lengthening until it fit snugly inside his snout, amongst his larger, flatter teeth. 

His airways opened up again and a rush of new scents and tastes flooded into his mind as he breathed. The overwhelming sensations nearly caused him to black out and his eyes fluttered as his irises flared with an intense purple color before shifting back to a startling blue. They’d grown as well, fitting into his larger sockets and widening his vision slightly.

Almost like it had eagerly been waiting, the green tinge of his skin rushed up his thighs as they too thickened and grew, the skin there stretching taut as the muscles underneath flexed. His briefs, already a size too small to help accentuate his favorite features for Raph, suddenly stretched beyond their limit and tore themselves apart, leaving nothing but tatters for Casey’s modesty. 

As the mutation worked its way up to his crotch, the searing heat turned suddenly docile, almost pleasant as it coursed between his thighs. 

He found himself panting, his body alight with a buzzing tingle as his dick suddenly hardened and grew. It was the most intense feeling of pleasure he’d ever experienced, and it doubled, then tripled, and then quadrupled to the point that he was thrusting into the air and screaming for release. 

His cock was fully hard now, leaking a river of clear liquid from its tip until the green color rushed down his length, instantly followed by changes along its path. His length thickened and grew just like the rest of him, the green pigment hastening upwards and causing it to twitch and shudder. The very human, mushroom-shaped tip rounded out slightly to match Leo’s and Raph’s as Casey gasped and moaned lewdly, his body sweaty and slick as he lost all control of himself. 

Feeling the changes rush down into his balls, Casey let out a gasp of pleasure as his testicles thickened and enlarged. His sack grew along with him and he felt his enlarged balls’ hefty, masculine weight pulled down by gravity as he shifted on the table. Finally, he was able to open his eyes and behold his new, larger, impossibly perfect tools as they bobbed between his thighs. 

As the heat began to ebb, Casey felt a pulsing above his backside and lifted his hips slightly. A nub of skin had grown and slithered down between his ass and as he moved, it began to twitch and flick on it’s own, a flood of nerves connecting the new appendage to his brain and he knew he’d just grown a tail. 

A rush of endorphins flowed through him as his ass clenched and grew, the proportions of his body finally equal. He leaned back onto the table, feeling his shell propping him up slightly as he moaned lewdly again, his cock spurting jets of precum over his plastron. 

Everything was blurry. The world seemed to have shifted around him and a haze had descended on the laboratory as he breathed slowly, in and out. He ran his hands up and down his arms, his head, his legs. The texture of his skin had changed; it was toughened and scaley and slightly slick now.

It almost felt like he was watching everything in slow motion as his eyes flicked around the room, finally landing on Raph’s face. 

“Caseyy… whyyy… why’d’youu smellll soooo gooood?” 

The massive turtle’s voice was slurred and slow, almost like he was drunk. His words buzzed pleasantly in Casey’s ears, each extended syllable flowing like a rich piece of music through the air. 

To Casey’s, the world around him felt like it was slowing down as well. 

There was a light haze building up around them, clouding everything and making it hard to think clearly. 

But at the same time, he felt… incredible.

He was lighter than air and so intensely pleasured at the heated thoughts swirling around his mind.

Casey tilted his head, somewhat confused as he turned to see Donnie beside him, the genius's eyes locked on the throbbing length between his legs. 

“Donnie?” Casey said, his mind foggy and body tired, despite the energy he still felt coursing through him. 

“Mmmm… C-Caseyy, I juust neeeed to… lemme… tasteeee yourr….” 

Slowly, Donnie bent forward and moaned deeply, wrapped his lips around Casey’s leaking cock. Though it seemed that even as a turtle used to his brother’s various sizes, Donnie couldn’t easily fit Casey’s length inside his snout. The genius flicked his tongue over Casey’s leaking tip and ran his hands up his length simultaneously. 

The instant pleasure that filled Casey was indescribable. He bucked his hips hard, causing Donnie to gag slightly but like a drone, he pressed on and continued to plunge Casey’s length down his throat. 

Already, Casey could feel his balls churning with potent, hot seed and he knew he wouldn’t last much longer. Raph was still beside him now, his own prodigious cock leaking endlessly, slick as could be, and a welcome sight to Casey who reached out and grabbed it wordlessly. 

Raph grunted and bent forward, capturing Casey’s snout with his own. Their tongues, finally equal in size, slid over each other and plunged deeply into their maws, twisting and rubbing and tasting. To Raph, Casey tasted… new, and hot, and endlessly delicious. It really was like a drug to be around him. 

And Casey tasted Raph for what felt like the first time, his scent filling his nostrils and his taste filling his throat. As Donnie wrapped his tongue around his cock, Casey pulled Raph closer and couldn’t help but wrap his thicker arms tightly around his lover, easily pulling him on top of his new body. 

Raph ground his cock over Casey’s plastron and then, with a swipe of Casey’s tongue, felt himself explode, shooting jet after jet of fresh cum over Casey’s chest and neck.

Casey thrusted into Donnie’s mouth once, twice, and then finally, knew it was too much to hold back and he blasted the slender turtle with his first orgasm in his new body. Donnie had to pull off of him after the first blast, leaving Casey’s dick to pulse and shoot his fresh seed all over Donnie’s face, and then Raph’s backside and shell. A seemingly endless volley of cum was sprayed down on all three of them and their combined efforts seemed to cause all of them to collapse. 

Donnie bent forward and leaned on Casey’s still spurting cock, breathing in the heavy musk and sweat that emanated from the new turtle’s nether region. Raph, utterly spent, laid on top of Casey entirely, his weight not nearly the issue it would’ve been had Casey still been human. 

And at last, Casey laid on the table, his newly grown shell still propping him up slightly and supporting both he and Raph’s weight. 

The light of the room seemed to dim as the afterglow of his body’s intense first orgasm subsided. Quickly, Casey found himself losing his vision as blackness encroached on the edge of his consciousness. 

And then suddenly, his eyes closed and he fell limp on the table, the black of sleep letting him finally drift away.