Backdoor Affair

Fresh from the shower, his light grey fur still slightly damp, Theo tossed himself onto his bed with a sigh, the bed springs squeaking slightly as the 15 year old pitbull reached a paw towards his phone, grabbing it and reclining against the stack of pillows under his back as he grinned. Shoving his crotch in his other hand, the teen used his thumb to gently tease and play with the tip peeking out from his sheath as he quickly navigated to the site he'd become so familiar with in the recent few months, letting his cock grow into his fist as he opened up the search bar of his favourite porn site, typing in only a few letters before his phone's autocomplete already suggested the exact words he had in mind, 
"Anal teen" 
Theo was a little bit of a late bloomer, at least in terms of his libido, as he'd only recently begun to earnestly lust after girls, his masculine side only beginning to show a few months after his 15th birthday. He'd joked around with his friends and even had a tiny bout of puppy love with one of his class mates, but it took a few years into his puberty for his sexuality to actually kick in. But when it did, it hit the young canine like a ton of bricks, suddenly finding himself in what felt like a years worth of pent up lust all coming down on him at once. He quickly also found himself gravitating towards a very particular niche, enjoying butt-stuff of all sorts ten times more than any other naughty antics, nearly all of his jacking off getting done to pictures of ladies getting their tailholes eaten out or to videos of squealing women getting a thick knot in the rear. The boy didn't know why he had a particular preference for asses, occasionally pondering whether it was simply because of the sort of porn he was exposed to first, but he wasn't about to start questioning what his lower half desired, happy with whatever as long as it got him off. Theo wasn't sure whether his parents knew what was going on in his private life, always feeling slightly awkward whenever he'd sneak into the bathroom to take care of an inconvenient erection right in the middle of movie night, but he was rather thankful that they'd both recently had a surge of busyness at their work, often leaving him in charge of the house for days or even weeks on end. The teen had the house to himself for the entirety of the week, and between that and his summer break from school, he didn't have too much to worry about except making sure the little man between his legs was kept happy. 

Scrolling through the newest postings that had been uploaded since his last visit to the site earlier that morning, Theo tried to gauge his interest in the videos based on their thumbnails, a cavalcade of women bending over and spreading their cheeks for him as he panted and gently pushed a finger into his sheath, sliding it back and forth as more and more of his girth rolled out, giving a soft gasp as his gradually inflating knot popped out. Salivating for a sample of the offerings, the boy tapped on one of the videos showing a chubby and bottomless bear cradling a canine dildo in her arms, biting his lip as the video loaded for a few tense seconds, finally coming to life with the MILF-y bear grinning down at the camera she'd set up on her bathroom floor. She squatted down and pulled her ass cheeks open, shaking her rear right at the teen as he pumped his cock, precum drooling through his fingers as he moaned. The bear grabbed her pre lubed dildo and brought it behind her, setting it onto the ground and aiming her tailhole against the tip, her hand grasping at the knot just the same way as Theo was, her plump donut stretching slightly as she teased the tip of the silicone shaft, plucking at her pucker as she giggled. The second before the woman sat down on the dildo, the video paused and was replaced by a call screen showing the cub's neighbour's name, the loud ringtone startling the pitbull enough for him to let out a decisively unmanly squeak as he flinched. Fumbling to answer the call and bring the phone over to his ear, one hand completely soaked in precum, Theo shouted out sheepishly, 
"H… hello?" 
"Hey, I hope I'm not interrupting anything." 
"Nope, no, just… lounging around. What's up?" 
"Me and my husband have some pretty urgent business in the next city over, and it's probably gonna take all week long. Is it ok for Liana to stay over until then?" 
"Of course, no… no problem whatsoever…" 
In a slight panic, the boy looked around his room, trying to find where he had tossed all of his clothes to as the woman on the other end continued, 
"Great, thanks so much, as usual! I'll send her over now."
"O… okay, bye!" 
Tossing his phone onto the bed, the canine shot up and sprinted to dig through his desk, trying to push his determined erection down as he grabbed a pair of boxers, yanking them on as he tried to listen for any sounds coming from downstairs, knowing that Liana wasn't the type of girl to just patiently wait at the door until let in.

Just as Theo had pulled on a pair of sweatpants and a t-shirt, he heard the back door clicking open, the bright and cheerful voice of a little girl ringing up to him, 
"Hey, Theo?" 
"I'll… I'll be right down, just a sec!" 
The teen grabbed his phone, his heart jumping for a split second as he noticed the paused porn video still lighting up the screen, a bead of sweat rolling down his face as he stared at the bear's tailhole being opened up by the dildo, quickly closing the browser and stuffing the phone into his pocket as he jogged down the stairs. As soon as he made it to the first floor, a tiny golden retriever jumped out at him from behind a corner, her fangs bared and her arms raised as she let out a playful growl, getting the boy to jump for the second time that day, though thankfully he was able to hold back the girly scream this time around,
"Liana, c'mon, don't do that to me!" 
The five year old pup giggled and hugged Theo, dressed in a glittery shirt and a black pair of tights leggings, her tail wagging as she squeezed him by his waist. He pet the young golden's head, trying to subtly angle his crotch away from her to hide the waning erection still poking at his underwear, relieved as she finally let go, bouncing towards the TV, 
"I was right in the middle of watching The Duckling Adventures when mom and dad had to leave, I don't wanna miss the whole show!" 
Theo watched with a smile as the cub dove belly first onto the sofa, snatching the remote and turning the TV to her favourite show before settling down, waving for him to join her as well. Both dogs were without siblings, and their parents had been close friends for decades already, which meant that the pair bonded very quickly even with the ten year age difference, treating one another as the siblings that they never had. Being neighbours, Theo spent a lot of his free time watching the young golden retriever, having taken care of her when she was still in diapers. The boy sat down next to her on the sofa, his smile only widening as Liana immediately cuddled up against his side, immersed in her cartoons as let out a content sigh. 

Enjoying the TV with the little girl, Theo leaned back and relaxed, though Liana didn't seem to be able to settle down quite as easily as he had, fidgeting and flopping all around the sofa every few minutes in an attempt to find a comfy position, crawling over the pitbull's lap several times to get to the other side. Every time that the cub clambered over him, Theo found himself getting slightly more distracted, a familiar problem rearing its head in his pants as he saw her rear stuffed in the snug leggings, much to his horror and surprise. He hadn't ever thought of the girl as anything more than his little sister, but being interrupted right in the middle of his daily ritual left his head in a rather mixed up state, forcing him to for the first time actually notice just how plump the golden retriever's flank truly was. The teen tried not to stare at the neighbour's rear as she squirmed around, just barely managing to focus his mind somewhere else before the bulge in his sweatpants was big enough to be visible, thinking up of some good excuse that he could use to disappear for a few minutes and take care of the unfinished business. Just as Theo was about to stand up, the pup suddenly got a great idea for a good place to cuddle up on, hopping onto his lap and sitting down, nestling her head against his chest as she cooed softly, finally getting comfortable. The boy bit his lip in an effort not to scream out loud as he watched the cub settling down, wriggling around for a few moments to get cozy with the weird hard lump pressing against her butt, finally managing to angle herself so that the bulge nestled between her ass cheeks. With precum already starting to soak into the front of his boxers, Theo held his breath, afraid that the puppy might hear his heart thumping like crazy in his chest and get curious about his nervousness, all attempts at stopping his erection from growing failing horribly. His previous plans of getting far away from Liana were tossed away as soon as he felt her soft cheeks squishing against his crotch, her tiny wriggling massaging his knot as if she knew exactly what she was doing and was deliberately attempting to tease him. He was very happy that his tail was buried between his back and the sofa, as it would've definitely announced his excitement to the oblivious girl if it wasn't hidden away. 

Theo tried desperately to not do anything dumb, but there was no way for him to handle the little girl's warm ass on his lap while acting like absolutely nothing was happening. His eyes were completely off of the TV and focuses on the sight in front of him, the golden retriever's thick cheeks pushing on his thighs as she rocked back and forth in rhythm to the theme tune of the cartoon, making his lips quiver as she inadvertently milked another squirt of pre from his shaft. His cock was pointed up, the tip very nearly poking out from underneath the band of his sweatpants, his hands shaking as he carefully reached one up to pet the girl's back, just as he had done countless times before, though this time around his mind was in a very different place. Feeling the bigger canine's hand rubbing at her back, Liana gave a soft moan and wagged her tail, leaning forward slightly to better let the teen scratch her back while she focused on the cartoons, still slowly wiggling her butt back and forth, not paying any attention to the throbbing of the hard knot underneath her. With trembling breath, Theo slowly let his hand wander further down the cub's back, massaging her lower back while building up the nerves to take the final step, finally shifting his palm to her ass, letting his hand rest on one of her soft cheeks. He didn't move his hand around, trying to gauge her reaction, his anxiety easing just a tad as soon as he noticed that Liana didn't seem to mind his hand resting on her flank. Pushing his luck just a hair further, he very slowly and gently clenched his fingers around her bun, getting a careful squeeze of her rear. As soon as he got a handful of the little cub's backside, the pitbull shuddered and creamed his underwear, moaning with a heavy blush as cum spurted through his boxers and wet the front of his pants, a dark patch appearing on the sweatpants as he quickly let go of Liana and tried to disguise his moan as just a yawn, resuming his more innocent petting while panting, his legs still flexing every time she shifted her butt around and rubbed it against his sensitive knot. 

After withstanding a few more minutes of the accidental grinding, Theo finally managed to push through the worst of his lust-induced brain fog, gently lifting the girl off of his lap and smiling through his gasps as he made up an excuse about needing to go make dinner for them both, taking the opportunity to first clean himself up a little and change his soaked underwear. The rest of the day went by with very little of note, the teen's horniness mostly kept in check, the occasional visit to the bathroom taking care of any awkward boners whenever Liana danced around and shook her tail to the beats of the radio, an act that she loved to do very frequently. While setting up the mattress for the cub in his bedroom, the boy couldn't resist taking another "accidental" grope at the golden retriever's buns, pretending that he was just playfully shoving her off of the mattress so he could get the bedsheets on. Through the night, Theo's careful tone began changing however, as the pup sleeping a step away from him made the teen a bit hesitant about relieving himself before bed as his usual routine dictated, leaving him in the grips of horrible lust the next day, his morning wood nearly pulling his blanket off of him. Waking up, he was very tempted to take the risk and jack off before Liana woke up, hoping that he could keep his head straight and not touch the girl if he nipped the issue in the bud, but she unfortunately stirred from her slumber only a few minutes after him, full of energy and ready to stick to his side like glue once more. He just barely managed to hide his hard on through his morning routine, further tempted by her delicious flank stuffed in nothing but a pair of pink panties, his feral needs pushing him to give her ass another few squeezes throughout the morning, some disguised as playful pinches and others as pure accidents, each almost causing him to require another fresh pair of boxers. 

Trying hard not to arouse suspicion or come onto the cub too hard and freak her out, Theo kept his fondling to as little as he could, though her choice of leg wear was definitely making it very difficult on him, her leggings leaving quite little to the imagination. He also didn't just want to completely isolate himself from the cub either, since he was supposed to be looking after her after all, and the teen did genuinely love every second that he spent with Liana, not just for her assets. He was mostly able to control himself, cooking up breakfast and having a little fun in the backyard with the puppy, but her requested piggyback ride did put a slight blush on his cheeks as she clung to his shoulders, almost forcing him to feel up her bottom to hoist her up, though he wasn't exactly complaining about that. Managing to keep his hands to himself for the most part, the pitbull coasted into the afternoon, thinking he might've finally gotten a handle on the situation, stepping away from the golden for just long enough to stick some fries and fish sticks into the oven. He walked back into the living room, dusting off his hands with a smile, 
"Alright, dinner's gonna be ready in j… just a few… minutes…" 
Trailing off, Theo found himself enamoured by the sight in front of him, almost losing the ability to speak as he stared. Liana was lying on the sofa belly down, a pillow propped under her hips, her feet waving in the air, her round ass sticking up as she thumbed through a comic book. With his shaft pointing the way forward, the teen walked over and sat down onto the sofa next to his neighbour, laying both hands down on her rear, her tail giving a slight twitch while she stayed focused on her comic. Pressing his thumbs into her soft mounds, squeezing and kneading like he was working on a loaf of bread, Theo massaged the little girl's ass, getting a few giggles from her, 
"That tickles!" 
Lowering his head, the teen was a hair away from yanking down the cub's leggings and shoving his face between the cheeks, pulling himself back at the last second and running off into the bathroom to relieve some of the pent up lust fogging his mind. 

For the next couple of days, Theo kept up with the fondling and feeling up of the puppy's ass, now determined to get further than before with the girl, giving her butt a cupping at every opportunity he could to groom Liana into being more comfortable with it. Four days into his babysitting gig, the pitbull decided that he needed more than just some touching, walking into his room to find her sitting on his bed playing on his console, dressed in one of his shirts and pink panties, the oversized shirt hiding most of the underwear as she grinned up at him, 
"I didn't wanna run back to my house for another shirt, so I borrowed one o' yours, hope you don't mind~" 
Theo only smiled, sitting down on the floor in front of her, letting the cub flop her legs onto his shoulders as she mashed at the controller, her tongue sticking out in concentration. The boy was about to make her concentration a whole lot more difficult however, turning around and getting onto his knees, lifting up the girl's shirt and gingerly stroking her ticklish belly as she squirmed, 
"Theo, stooop~! I'm almost at the end of the level." 
The teen smirked and grabbed Liana's ankles, slowly lifting up her legs as she rolled back slightly, giving him a better peek at her flank as her face turned a similar shade of pink as her panties, 
"Wh… what are you doing?" 
"Just something really fun, you'll see~" 
Theo shoved his snout right underneath the golden retriever's taint, pushing the fabric of her underwear into her asscrack as he nuzzled his nose between her beautiful buns, taking a good sniff of her ass, moaning as the delicate scent of floral soaps and just the tiniest dash of a feminine musk filled his nostrils, his hand pushing down his pants and squeezing his red rocket as a heavy flow of precum wet the carpet. Feeling the gusts of air from the larger canine's inhales and exhales tickling her sensitive bud, Liana moaned quietly, her legs resting on the teen's shoulders as he pulled her panties off to the side, sticking his cold nose right against her tailhole, heavier moans erupting from them both as she almost dropped the controller on his head. 

Taking in the little girl's heady fragrance, Theo channelled his inner feral canine urges as he sniffed Liana's ass, poking at her butt while she bounced between giggling and panting, unsure of why exactly the odd nosing felt so good. Losing almost all control of himself, the teen pulled his snout out from underneath Liana's backside for just long enough to stand up and guide her to get down on her knees and elbows on his bed. The cub noticed the stiff rod poking up from the pitbull's pants, but didn't understand enough to care too much about it, her mind half focused on both the video game and the weird tingling taking over her body as she bent over and stuck her ass up. Crawling behind the pup, Theo got down on his back and pushed himself underneath the retriever's flank, one hand pumping at his cock as he reached the other to grab the base of her tail, gently guiding her ass down onto his face, her pink panties still pulled to the side, her adorable pucker left exposed. The boy carefully poked his tongue against the little donut, feeling the slightly puffy rim quivering as he licked at it, the younger dog's heavy breathing changing into moans. Liana at first seemed like she was about to pull her ass away from Theo, but he was pleasantly surprised by her butt instead pushing down against his face, her cheeks enveloping his muzzle as he continued lapping, precum gushing from his tip like a fountain, rivulets streaming onto his knot as he jerked off and humped his own hand, the springs on his bed creaking rhythmically. The teen circled the tip of his tongue around Liana's tailhole a few times before finally slipping inside, tiny grunts and huffs coming from her as he dug deeper into her delightfully tight asshole, his nose bumping against her still-covered slit while he rimmed her. After only a few deep licks, Theo's girth erupted like a volcano, thick ropes firing up all over his belly and shirt as he groaned against the golden retriever's hole, still gripping his knot as he quickly pulled his face out from underneath her, pulling her panties back on with a near-ashamed blush. Liana looked back at the boy as he struggled to stuff his cock back into his pants and wipe away the sticky mess from his belly, slight disappointment on her face, 
"Why'd you stop?" 
"I… I gotta go put the pizza in the oven…" 
The pitbull walked away, disappearing downstairs to clean up. 

With his lust satiated for the day, Theo was able to get through the rest of the day without giving in to his desires, though his will was tested harder than ever right before bed time. Walking into his room, he found Liana already lying on her mattress on the floor, her butt pointed towards the door and her legs spread, her panties pulled down to her knees as she wagged her tail and looked over her shoulder, 
"Can you do that kissing thing to my butt again? It felt really good!" 
Instantly popping a boner and almost jizzing his boxers on the spot, the stunned teen could only nod as he dropped to his knees behind the retriever, grabbing her ass cheeks with both hands and spreading them open, diving into her tailhole and nuzzling his tongue as deep as he could go. Liana squealed in delight at the thorough rimming, pushing back against the pitbull's maw as his tongue dredged her ass, her legs shaking as he moaned and stroked her butt. Tugging his already drenched pants down, Theo let his precum spray onto the bedsheets below as he ate out the young girl, his lust building to immense levels as he pulled his face out from between her ass cheeks, thick strands of saliva stretching out between her open tailhole and his lips. Liana was just about to complain about the sudden stop, when she felt something else prodding at her hole, looking over her shoulder to see the boy's hand fondling her taint, a finger poised to stretch her wider. He slowly pushed the digit in, using his own spit as lube as he gave it a slight twist to work it in, both the golden's shoulders and her pucker tensing up as she gave a small grunt. Theo let her adjust to the new feeling for a moment, waiting for her asshole to relax again before pushing deeper, giving her a few good thrusts before adding another finger inside of her, leaving her a moaning and shivering wreck. By the time her snug tailhole was stretched around three of his fingers, the cub was gasping and clawing at her pillow like a bitch in heat, long strands of her honey drooling from her pussy lips. 

Shaking with excitement and lust, Theo lined his shaft alongside the fingers stuffed in the golden retriever's asshole, trying to see how gaped she was as he debated taking the final leap, feeling like he couldn't hold himself back. Clinging to her pillow and suckling on the corner of it, Liana let out a tiny squeak as she felt the fingers pulling out from her ass, panting hard as the boy flipped him around onto her back. With her panties flopping around her ankle, she watched Theo pushing the tip of his cock between her ass cheeks, staining her golden fur with precum, 
"Wh… what's happening?" 
Out of breath and with saliva smeared across his muzzle, Theo pet the little girl's chest with a reassuring yet lusty smile
"It'll make us both feel really, really good~" 
Fully trusting the boy she thought of as her big brother, Liana tried to relax and lay still as the shaft split her buns apart, pressing against her stretched open asshole, her body tensing up slightly. Lined up with the retriever's passage, the teen took both of her hands, holding them in his as he leaned down over her, pressing their lips together and stealing her first kiss. Liana was used to the sorts of kisses that she shared with her mom or dad, but was slightly taken back by the pitbull's tongue invading her maw, her face glowing red as she whimpered softly into his mouth. With both canines hugging one another, Theo thrust into the pup's tailhole as gently as he could, her arms squeezing him harder as she squealed for the first inch or two before relaxing, writhing around underneath him as he buried his girth all the way up to his knot. With the golden retriever's asshole flexing against his knot, the boy broke the kiss and stared down into the moaning cub's eyes, smiling at her blissful look as he whispered,
"I love you~" 
"I… I love you too~!" 

With the tender moment driving Theo's lust into overdrive, he rolled the girl back onto her belly, wrapping an arm under her belly and lifting her up onto all fours, nuzzling his cheek against hers as he began pounding at the puppy's tailhole. Feeling the teen's crotch thumping against her soft ass cheeks, his throbbing shaft plunging into her pucker and awakening sensations that made her head spin, Liana buried her snout into her pillow and moaned into it, not wanting to wake up every single house in the entire block with her howling as she pushed back against Theo's cock. She didn't know what was happening, nor did she know the names for the odd feelings wrecking havoc throughout her body, but she did know that she wanted as much of the pitbull inside of her as possible, her tail flogging his belly while he stuffed her tailhole. With the weird sensations building up more and more in her loins, Liana grabbed a mouthful of her pillow, letting the mounting pressure sweep her up as she had her very first orgasm, moaning and huffing hard as she clenched down, soaking her own thighs in the process. With the cub milking him like her life depended on it, Theo knew he couldn't hold on for much longer, debating whether he should try to knot her while he still could. Not wanting to risk it by forcing the tiny girl to take a knot in her tailhole during her first mounting, he slammed as much of his girth inside of her as he could, letting her trembling orgasm work him over the finish line as well. With a loud yell, the teen blew his load and creampied Liana, the hot rush of seed filling her asshole while she drooled on her pillow, a few drops seeping from her pucker and dripping down her wet mound. Collapsing on top of the puppy, still hugging her, Theo and her both just panted and cuddled for a few minutes, gasping and whimpering every now and then as an involuntary twitch or clench struck them, barely able to even keep their eyes open. Rolling onto his side, still hilted in Liana, Theo pulled her blanket over them both, kissing her neck and licking her cheek as she slowly fell asleep in his arms, tuckered out after a hard day.