“I’ll be back in no time, don’t look for me!” Alvin called out loud, making sure he would be heard before shutting the door behind himself.  

Just another normal Saturday morning here.  Theodore was watching cartoons in the living room, Simon was reading in their room, Dave had slept in, heck even Alvin was still in his pajamas.  No one would suspect a single thing.  Alvin hummed, the grass crunching quietly beneath his feet as he marched through the backyard, going for the treehouse they had set up.  

There was a rope ladder that lead up to the door, and Alvin climbed it in no time.  He pushed open the door, letting out a light grunt as he climbed on in, drawing up the ladder and closing the door.  The wood walls were bare, there were rugs here and there, and there was a window cut out of each wall, and a medium sized chest just for storage.  The only bonus really was that they had a pile of bean bag chairs.  But, none of that made Alvin falter.  

Ah, the treehouse… No wonder they barely came out here.  It wasn’t much of a looker at all.  The munk looked all around, arms resting behind his head.  “Now where did I put it…?  Oh!  Duh.  Where else, Alvin?” He said as memory returned to him.

He bore a cheeky smile on his face, grabbing a red beanbag and tossing it to the middle of the treehouse, letting out a little hum as he went to the chest, opening it up.  

“Alright… let’s get to business~” He says as he leaned into the chest, rummaging around.  Theodore just had to keep his extra plushies in here… “Aha!  There we go!” Alvin said as he found his item.  It was a regular old thermos.  Walking back to the bean bag, Alvin set the thermos down and immediately started undressing himself.  His shirt went first, followed by his pants, and lastly his briefs.  He even tossed his signature cap aside.  

Now fully nude, Alvin crouched down, twisting off the thermos’ top before he held it upside down, watching as a pinkish substance oozed right out, plopping messily on the floor.  To think Simon had found it there… To think he had him drink some of it that one time at rehersals!  What a waste that would’ve been!  

“C’mon, don’t act all shy now.  I woke up hard, so I wanna get this done fast.” Alvin said as he prodded the mass of pink, watching it gurgle about as it started to expand.  Slowly but surely, it grew and grew until it was right at Alvin’s height, reshaping itself until… It looked just like him.  Only with a pink tint to, well, everything, but other than that it was a perfect copy!  

The second Alvin then stretched, groaning as it rubbed around its throat.  “Hmph… when do I get to go back to that basement?  The nerd was at least studying me.” It spoke with a somewhat distorted voice that was almost like Alvin’s own.  

To that, Alvin waved a hand dismissively.  “Look, Pink, if you really wanted to go back so badly, you would have gone by now.  Cuz I know you can.  You can climb out a thermos without a problem.  Now then, how about less talk and more work, hmm?  We’ve got something to deal with.” Alvin said, pointing down at his crotch.  All this time, he was sporting morning wood.  Those sorts of dreams were becoming more and more frequent ever since that werewolf mishap... But this was a good way to fix that.  

Pink let out a groan, rolling its eyes.  “I know you have hands.  You can do this yourself.” To that, Alvin grinned proudly.  “I could,” he said, “but why would I do that when I could give you something to do while you wait?  Look, just do this one more time and I’ll take a back to Simon’s lab so you can do… whatever you’re trying to get there for.”

Staring Alvin down, Pink grumbled, but nonetheless sighed, laying itself down on the bean bag.  “Fine, fine… Just hurry up.  I don’t want anyone else finding me.” It spoke.

“You’ve already been in Si’s basement.  I’m surprised he hasn’t broadcasted it all over town.” Alvin said, poking his tongue out of his mouth before he moved around to Pink’s head, facing it’s feet while he angled himself, his balls and cock swaying side to side as he aimed for Pink’s mouth.  Then, he dropped down his hips, slamming himself in all the way to the balls, his sack smacking against Pink’s nose as he moaned out loud, arching his back a little as he starts to thrust right down.

Pink let out little grunts each time Alvin’s hips met its face.  Thank goodness it didn’t need to breathe… Once Alvin started, he wouldn’t stop for anything.  He had way too much energy, even for an early morning.  Pink grumbled out each time Alvin hilted in its maw, using it’s tongue to caress his cock as it went in and out.  It didn’t understand why he insisted on doing this, but it at least got results.  

“Mmf… Yeah, that’s it… work that tongue!” Alvin praised, gripping into Pink’s gooey sides, lightly squishing the substance in his hold while he kept on humping, pre dripping from his tip here and there.  “Gaaah, never thought you’d be good for this… much better than a hand, that’s for sure.” Alvin huffed out, closing his eyes as he kept to his eager humping, angling himself up so he could grind on Pink’s soft, squishy tongue.  “That’s the stuff~” He moaned out, keeping his hold tight on Pink’s body.

The shapeshifter rolled its eyes, reaching up to grab hold of Alvin’s soft ass, groping into it while also holding him steady, taking over the motions by bobbing its head a little.  It was nice getting the chipmunk to moan like that… it at least meant he was on his way to peaking.  Pink let out a little grunt, this time coiling its tongue around Alvin’s length.  

The task may have been a little degrading at first, but at least it got some sort of food out of it.  One of its fingers extended, losing its definite shape as it moved in between Alvin’s cheeks, prodding his hole a few times.  The action made Alvin moan louder, his downward humping getting rough enough to make Pink’s entire form jiggle.  And when that digit breached Alvin’s rim, the chipmunk threw his head back with a loud moan, squeezing both the bean bag as well as Pink’s waist.  

“You sneaky little… mmnh, get deep in there!” Alvin ordered, his cheeks flushed as he found himself sitting on Pink’s face, careful to not squish the shapeshifter while he rode against the invasive finger, rocking his hips so he’d still be humping into that warm, soaked mouth.  As if getting his dick worked early in the morning didn't feel good enough!  “Yeaaaah… keep that uuuup~” Alvin moaned, his hands moving up to his chest, pinching at his own nipples in between humps.  Feeling Pink’s finger, or whatever it was now, burrowing further inside of him was sending all sorts of shocks through his body.  Alvin stirred his hips around, trying to maneuver that digit around himself.  “You’re so close… get the spot!”

Pink obliged.  Between coiling his tongue on Alvin’s shaft, being a temporary fuck toy, and lavishing the munk’s ego here and there, fingering him didn’t seem too bad. It’d be lying if it were to say the rhythmic throbbing of the cock in its mouth wasn’t oddly enjoyable as well.  It’s finger stretched more, responding directly to Alvin’s moans.  The louder he got, the closer it must've been.  A theory proven true when a careless poke drew out a loud scream from Alvin, one that must've been heard throughout the yard at least.  If that dick wasn't bobbing before, it was now. 

With Alvin’s moans as a guide, Pink jabbed that spot again and again, each time forcing a newer moan out of Alvin’s mouth.  The munk didn't seem to mind, or even care, that he might be drawing attention to himself. 

“Ooohhh god… c’mon, Pink, don’t stop… I’m gonna bust!” Alvin moaned out, biting his bottom lip as he arched his back.  It’s not that he hadn't explored back there before… he just hadn't been able to reach that tender sweet spot on his own.  Now that Pink was constantly knocking at it, though, that drove Alvin crazy.  He tilted his head back, his tongue hanging from his mouth some as he wiggles his ass against Pink’s hand.  

With a huff, Pink gave his prostate another good poke, causing Alvin’s hole to clamp down completely and drawing a loud moan from the chipmunk.  Seconds later, Pink let out a soft grunt, eyes open wide as it gulped down every spurt of cum that Alvin gave.  Certainly salty, but with a bittersweet hint to the taste, Pink grumbled a little while it drank. 

Alvin always seemed to have a lot to give. 

When Alvin finally pulled out, he let put a heavy sigh, a hand resting on his belly as he laid on his back.  “Man that was good…”

“Good.  Then you can keep up your end.” Pink mumbled, slowly sitting up from the seat.  

“Ah ah ah… I’m not soft yet.” Alvin said as he reached up, grabbing Pink’s hand to hold it in place.  “Besides, you can go whenever you want, we’ve seen weirder things in the house.” With that, he gave a little tug on Pink’s hand.  “You know I need at least two to be done, so lay down and get in position~”

The shapeshifter sighed, shaking its head as it laid out on the beanbag once more.  “As you continue to remind me.” It grumbled.  

“By the way… can you feel?  Not like you really react every time I do this to ya.” Alvin commented, looking up and down his copy.  “Hey, shape up that butt too!  I’ve got more cheek than that!”

Pink rolled its eyes, its body steadily morphing to Alvin’s desire.  “Yes, I’m capable of feeling.  I just don’t act on it like you wou- Aah!” It ended up squeaking as Alvin interrupted by smacking it across the ass.  

“Not that kind of feeling!  I mean does it feel good when I’m doing all this?” Alvin asked with a grin.  “Tell my nerd brother to test that.  If you feel pleasure, then this just got a lot more fun~  And judging by the noise you made, I’m guessing you can!” Alvin grinned wickedly as he held on to Pink’s butt, feeling the slimy substance of its form taking proper shape.  

Suddenly Pink was quiet, opting to just look away and let out a low huff.  “That was just a response sound, is all… I don’t feel things like that.” it insisted.  Unfortunately, that was a lie.  Every little squeeze, rub, and slap Alvin did sent a twinge of pleasure all throughout Pink’s form.  It tried to ignore it, but to no avail.  One detail it neglected to include was Alvin’s more… personal parts.  

But now, with its arousal coming on, Pink felt himself forming a similar sack and shaft to Alvin’s, dripping with a light pink goo.  It rolled over, standing up once more in front of the young munk.  “B-Better?”

“Huh… Is my dick really that big, or are you trying to flatter me~?” Alvin asked as he noticed the growing cock, poking it on the head as he tugged on it a little.  He started stroking it, glancing up at Pink’s face as he did.  The resounding moan from Pink settled it for him.  “That’s it.  I’m gonna make you scream~”

“N-No need for that, honest!  I’ll just be on my way and- A-Aaah!  Goodnesssss…” Pink’s words died into a low moan, fighting to keep its form when Alvin started to tease it more.  It could feel the chipmunk right behind itself, their bodies pressed together while Alvin's paws ran up from its hips to its chest.  Pink looked off to the side, only to moan again as Alvin pinched both of its nipples, tugging them outwards just a bit.  “Wait, n-no, not there!”

“Hehe… for something that’s supposed to be me, you sure are girly.” Alvin taunted, tweaking those gooey nips at his own leisure.  “I think this is a definite you thing.  My nipples aren't nearly this tender~” 

“S-Shut up!  You were j-just messing with yours!  Besides… Who wouldn't react to this?” Pink huffed, arms crossing over its chest to protect its nipples.  Unfortunately, Alvin just got rougher then, working the pink buds between his fingers and squeezing them once again. 

Alvin smirked evilly as he heard Pink whimper and moan.  He could feel the shapeshifter quiver like jelly with each moan that slipped out~. “Nothin’ wrong with tender nips.  Just be honest about it~” he cooed out. 

Pink got ready to protest, but another sensation made it moan instead.  Alvin had started grinding against its butt.  At first, it was just cock against cheeks, with Alvin still moaning and taunting Pink with nonstop cooing and grinding.  

But, when he passed over Pink’s hole, or where a hole should have been, it didn't take the shapeshifter long to form one that Alvin continued to grind at.  

“Oookay… I’m gonna plow you now, Pink.  Any last words~?” Alvin asked. 

Before Pink could get another word out, Alvin burrowed in all the way, his hips smacking wetly against Pink’s jiggly ass.  The familiar feeling of Alvin’s shaft against its inner self was more intense this time.  Admitting it could actually feel seemed to make the pleasure more tangible than before.  Pink couldn't explain.  Even if it could form the words, it couldn't explain.  

“Mmn… N-Normally you just lay there.  You’re squeezing on me, Pink.  Just admit it, you love this!” Alvin teased as he got right back to his fevered humping.  He didn't care if drops of Pink’s goo were sticking to him as he thrusted. All that mattered was him bursting again.  That and driving the shapeshifter crazy~. 

Alvin leaned forward then, falling down on top of Pink as it landed on the beanbag. Under him, Pink fought to stay silent, even melting its own mouth away in a vain attempt at silence.  Regardless, muffled groans of pleasure escaped its form somehow.  It was even starting to lift up its butt into Alvin’s thrusts.  

And Alvin just kept going.  Seconds melted to minutes, time was a crawl, and the two of them were practically clinging to each other in no time.  Alvin's paws had slipped inside of Pink’s body when he went to hold the other “chipmunk’s” chest.  He was going to apologize, but when Pink let out a much louder moan, Alvin just smirked proudly. 

With a playful growl, Alvin swished his hands about inside of Pink, not minding any of the squishy pink slime his hands were gliding through.  “Shoulda been more solid!” He chided, panting softly against Pink’s neck as he pulled upwards, bringing the shapeshifter up with him.  Alvin changed their position, plopping Pink in his lap now.  One hand stayed inside of Pink, while the other came on out(dripping slightly) to grab Pink’s cock, pointing it up to its face.  “C’mon… lemme see what it’s like when you cum~” he teases, giving the head of Pink’s dick a good stroking.  

“Hnn… n-no, no stop… stop it, or I’m gonna… aaah…!” Pink shut its eyes, hands going up to rest against Alvin’s chest.  It couldn't help it.  The penis it created was still new, never touched before.  Especially at the head where Alvin refused to leave it alone.  

Pink felt an unfamiliar build up within, like parts of its inner substance were shifting around and moving down.  This hadn't happened before… “Mnn… s-stop… I don't think I can take iiiiit…” 

The begging fell on indifferent ears.  Alvin changed between rubbing that cockhead and bucking his own hips, watching Pink’s face as it contorted into more and more pleasured expressions. 

“Piiiink… if you cum before me, I’ll let you do whatever you want~. I’ll even take you outside the treehouse~” Alvin cooed, emphasizing his words by picking up speed.  “Mmn.. a-and if I’m first, well… you’re gonna have to stay up here~!”

Groaning, Pink tried to hide away its face.  “Don’t stop…!  Oh goodness it’s gonna-!” With a sharp gasp, Pink tensed up. Its shaft hardened as much as possible, and before it could even make a warning, a loud and drawn out moan was escaping his mouth as it started to cover Alvin in multiple strands of thick, dark pink goo, its hips bucking uncontrollably as orgasm wracked its gooey form.  

Soon after, Alvin slammed himself into Pink one more time, shielding his eyes from the spurts as he began to unload himself, his cum firing off deep inside of Pink’s ass as he released his own satisfied moan.  

The afterglow settled down like a heavy blanket.  Alvin was panting away, Pink was still trying to recover, and both of them were just a mess. And, of course, Alvin was the one to break the semi silence.  

“Well, looks like you popped first… Guess I’ll be taking you to Simon’s lab again.” 

Pink grimaced at the thought, though it didn’t understand why.  That was the goal, wasn’t it?  

“...And what if I want to be in both places?” it asked quietly.  “That was the first time our session’s ever felt so… intense.”

Alvin chuckled.  “Awwh, you’re in love with the way I dick you down~” Alvin cooed, squishing his copy’s cheeks playfully.  “Let’s go and show Simon your new form, hmm?  I’m sure you can sneak your way back out here whenever you’re needy.” He said with a proud grin.  “We’re not gonna need the thermos anymore~” 

He didn’t even wait for an answer.  Alvin had gotten up to his feet, letting Pink off of his shaft as he started gathering his clothes.  “By the way, some of your… well, you is still clinging to me.  You might wanna get that.”

The shapeshifter bit its lip, looking down itself.  It was holding his form still… and it couldn’t make that shaft melt away, not when it was still a little stiff.  It glanced over at Alvin dressing, eyeing him up and down.

“Y… Yes.  That’d be great.”