Archive of Our Own ^beta

No good deed goes unpunished. Even though they're training to be professional heroes, they're not there yet - so when they’re on their way to grab some breakfast from a nearby conbini and Bakugou witnesses Kirishima stick his nose into someone else's business, and end up turned into an 80 lb black furred wolf as a result, he can't help the exasperated groan that rips from his chest.

“For fuck’s sake, Kirishima. Why the hell did you have to go and do that?”

The wolf flattens his ears against his head, ducking slightly as a trots along next to Bakugou. Some people give them a large passage and wide-eyed stares as they pass by on their way to U.A., but most pay them no mind. Sure there's a giant ass wolf walking down the street but what else is new?

“What am I supposed to tell Aizawa-sensei…” He mumbles as they near the gate, and as they cross he scans both of their ID cards and they make their way immediately to their homeroom teacher’s office for guidance.

“Send him back to his dorm room.” Aizawa says in a flat voice.

Bakugou blinks, glances down at the wolf at his heels. “He'll miss classes.”

Kirishima swings his head from one to the other, ears alert and flickering between them.

“It's not like he'll be able to learn anything like that.” Aizawa reasons. “He doesn’t look dangerous, but in this state having him in the classroom will only serve to distract the other students. Take him to Recovery Girl and see if there’s anything she can do.”

Aizawa turns to close the office door but Bakugou stops him.

“What about you? Can’t you do your-”

Aizawa interrupts him, “I already tried mine as soon as I saw him. It'll probably just need to wear off, but see what Recovery Girl has to say first.”

The door shuts in his face, and Bakugou looks down at his friend. Kirishima is sniffing his uniform pants and jerks away when he’s caught, expression appearing somehow embarrassed. Maybe it’s just Bakugou’s imagination.

“It has to wear off on its own.”

Bakugou swallows the shout he wants to bellow out, settling for a quiet, raspy “Dammit.”

“It will probably only last a day or two at most, but he shouldn't be left alone too long. He can't feed himself or use the toilet like this.” Recovery Girl continues, going over to her desk to scribble something on a piece of paper. “I'll write you permission to take leave of your classes today so you can do it.”

“What!? Why me?”

“I have an allergy to dogs.” She says matter-of-factly, then looks at Kirishima, who’s almost the same height as her. “Sorry.” She says softly, then louder to Bakugou: “Besides, he's your friend, isn't he?”

Bakugou glances down at the wolf sitting by his feet who’s bowing his head low as if in apology. Kirishima’s not going to be his friend after this shit is over.

He leads him back to his dorm room. He decides to take the old hag’s recommendation and take the day off from classes, no matter how big an inconvenience it is. He can afford to miss a day - it’s Kirishima who really, really can’t - so when he enters his room with the wolf at his heels he heads over to his desk and pulls out his textbooks. Wolf or no, he’s going to make sure the idiot gets his study time in.

But instead of staying at his heels as he’d done the whole way back to campus, Kirishima lopes over to his closet. Right, he should change out of his school uniform if he’s not going to class. The door is slightly ajar, and Kirishima shoves it open with his snout and noses around, audibly sniffing.

“What are you doing, mutt?” Bakugou growls, and then sees the large wolf knock over his laundry hamper. He flops over onto the pile of dirty clothes and rolls over on his back, wiggling back and forth and huffing through his mouth.

He’s rubbing himself in Bakugou’s scent.

Bakugou claps his hands. “Hey!” The wolf jumps up and walks back over, turning in half circles and looking all around as if confused. Bakugou thought Kirishima had retained his sense of self, but now he’s not so sure. He sits in the desk chair and motions the wolf to approach, and Kirishima follows, scampering forward to sit by his feet.

It’s strange how obedient his friend is in this new form. His eyes are dark and penetrating, his black stare boring into Bakugou’s and trapping him. He doesn’t blink or look away, and his ears and posture are straight and alert, as though waiting for a command. Bakugou can’t tell if this is Kirishima’s normal level of attentiveness, made more pronounced by his inability to talk, or if this deference is a result of his new wolfy instincts. Either way, those black eyes are making the hairs on the nape of Bakugou’s neck stand on end, some primeval part of his brain blaring off warning bells that this is a dangerous creature.

But it’s not, not really. It’s just that idiot Shitty Hair. He’s not going to rip his throat out.

“Kirishima.” He says, and is shocked by the faint waver he hears in his own voice. He’s not scared, he reassures himself. He just doesn’t know how to deal with- with all of this. “How much do you get?”

The wolf cocks his head to the side, expression unchanging.

That was a dumb question to ask, in hindsight.

Bakugou holds a hand out, palm side up, and says. “Put your… paw -or whatever- in my hand if you understand me. If you’ve understood everything that’s been going on.”

Kirishima looks down at his hand then back up, and brings a big paw to rest in the creases of Bakugou’s hand.

Ok. Ok, that’s good. Kirishima is still in there, at least in part.

It’s really something else, to see Kirishima like this. The most jarring thing is how quiet he is. Bakugou’s used to Kirishima chatting his ear off during their study times. He almost always has something to say, and if he has no commentary at the moment then he fills the silence with other sounds: tapping a pencil against the desk, humming, clicking his tongue against his teeth, breathing and sighing and laughing.

And Bakugou’s the kind of guy who appreciates his quiet. He doesn’t see the need for endless buzzing, but there’s something eery with the kind of quiet Kirishima The Wolf is. It’s unnatural, it’s calculating. It’s probably a figment of his imagination, but Bakugou is convinced Kirishima can see him better this way. It feels like a shield has been stripped away and he’s painfully bare before the wolf’s keen eyes.

“Are you actually paying attention or are you daydreaming about chasing squirrels.” He mutters, frustrated, after an hour of studying and reading aloud the notes from English. He’s so used to Kirishima giving him constant feedback, that now that there’s nothing he’s finding himself uncertain for once.

Kirishima’s mouth stretches open, tongue flopping out to the side and sharp fangs exposed as he makes a sound half-way between a wheezy pant and a whine, eyes crinkling up. It’s after a second that Bakugou realizes he’s laughing, and holy shit is that cute.

He looks away, willing himself not to blush or laugh back, but he feels a telltale heat creep up his neck. He stares at his textbook until his cheeks cool down, when he feels something wet and cold brush against his bare calf.

Bakugou jerks his leg away, knee banging against the underside of the desk in his haste. Kirishima skitters back a couple paces, his ears flattening along his head and his body low. His tail is curved up high and flutters side-to-side twice.

“What was that for?” Bakugou grumbles, and wipes away at the wetness on his leg. Kirishima lays down on the floor and drops his head between his paws, looking up at Bakugou from below. He already had some killer puppy eyes before he was turned into a wolf, and now their effectiveness has been doubled. It’s not fair.

“You wanna sniff me, don’t you? You freak.” He says it sarcastically, but he knows Kirishima will read the underlying question. Dogs smell each other’s asses to get comfortable with one another - and like hell Bakugou is gonna let Kirishima smell that - but he’s gathering there’s more of those lupine instincts at play here. He’s friendly, harmless Kirishima, but he’s also a wild animal. Like when he immediately went straight to Bakugou’s laundry hamper, his human sensibilities are being overruled by certain wolf urges.

Right now, it seems to be primarily scent related.

“Alright.” He slides his right leg across the floor, close to Kirishima’s nose. “Get it out of your system, do whatever you fucking have to so we can get back to studying. Just don’t go near my ass.”

Kirishima’s answer is more of that whiny yapping Bakugou has learned is how he laughs in this form, and then he’s quickly rubbing his snout all along Bakugou’s foot and calf, blowing out hot puffs of air through his nostrils, skimming the skin with his cold wet nose. Bakugou twitches away despite having given permission, the sensation ticklish, the rapt attention his bare foot receiving making him tense.

“That’s enough.” He says after a few moments that seem to stretch on too long, but Kirishima keeps going, working his way from Bakugou’s toes to his knees. He licks a spot on the inside of Bakugou’s knee and Bakugou hovers a hand over the beast’s head, the desire to push him away warring with the little voice in the back of his head telling him not cross something that could rip his throat out in one bite.

“Come on, Kirishima.” His voice is raspy and goosebumps pebble across his skin, run up his thighs. The sensation of the rough, firm tongue is not entirely unpleasant, and he’s shocked by how much he doesn’t actually want it to stop.

So when Kirishima pulls back, a swell of disappointment fills him, and he has to clamp his mouth shut to keep from telling him he can keep going. But he wouldn’t have had to, it turns out, because Kirishima shifts closer and resumes his ministrations, now on his inner thigh. He nuzzles his snout high up Bakugou’s thigh in the gap between his shorts and his leg, and licks.

It’s hot and wet and the rough texture makes Bakugou go still in his seat, eyes blowing wide, breath hitching. Kirishima licks again, shoving his nose further up Bakugou’s thigh, lapping at his inner leg as far up as he can go, his snout completely sheathed in Bakugou’s shorts leg. It’s bunched up around the juncture of his hip, Kirishima’s big pink tongue dangerously close to his crotch, licking at the sensitive skin there, coating the hairs in his saliva.

What the fuck. What the fucking fuck. This should not feel so… so good.

Bakugou’s cock is at full mast, stiff and interested within his clothes, twitching and throbbing each and every time Kirishima’s wolf tongue sticks out between those two rows of sharp fangs and licks at him contentedly. Does Kirishima know what he is doing right now? Bakugou knows he’s still in there, at least some part of him, but how much? Can Kirishima control what he’s doing? Is he completely under the influence of his animal instincts?

But every lick on his sensitive inner thigh makes his prick ache with want, just imagining how amazing that rough, wet tongue would feel if it were just a couple inches to the left, if there were no clothes on him and Kirishima could really get at him…

He doesn’t want to take the time to dissect this - what wanting this to happen must say about him as a person. It can’t be that wrong, can it? It’s still Kirishima inside there - it’s his friend licking at him, not some animal. He just… looks like an animal right now. Some part of Kirishima must be enjoying this as well, he reasons.

It’s too much. Clearly Kirishima is interested, so Bakugou unbuttons and unzips his shorts, and pulls his cock out. He shoves his tank top up to let his dick rest against his stomach, the tip already leaking with pre, and watches as Kirishima pulls his nose free of his shorts leg, nostrils flaring as he sniffs up towards the apex of his thighs. The cool moist nose nudges his shaft and Bakugou inhales sharply, teeth gritted and brows creased, pupils blown wide with lust. Just a little more, his muddled brain screams, and he holds his breath as Kirishima sniffs his cock for a few torturous moments.

His heart hammers in his chest, a nervous sweat beading at his temples, tension pulling his muscles taut at the sight of such sharp, long teeth mere centimeters away from his cock. Then Kirishima’s tongue pokes out and gives a tentative swipe across the shaft.

Bakugou sees stars. His head falls back and jaw drops on a silent cry, and he’s quick to hold his prick out at the base, presenting it like a treat to a well-behaved pet. And Kirishima seems to view it as such as well, as his tail starts to thump excitedly against the hardwood floor, tongue lolling out to lick thick, rough lines up Bakugou’s length.

“Good boy.” The words tumble from Bakugou’s mouth before he even realizes it, and Kirishima reacts by going faster, tongue working over his sensitive dick with a sort of frenzy covering the whole thing in hot drool. He laps up the precum that’s beading at the tip, tail swishing against the floor in little arcs, nose puffing out hot against Bakugou’s pubes. Shit, it’s so hot, it feels better than anything Bakugou could have imagined.

Kirishima moves down to lap at his balls, moistening the wrinkled skin there and pushing his nose all around the area. The scent must be concentrated there, because despite Bakugou’s miffed grunts when he doesn’t return to giving attention to his dick, Kirishima keeps showering the area with attention until it starts to feel uncomfortably sticky and wet.

His wet nose trails down lower still, slicking up his taint. Bakugou's cheeks erupt in flames, but even though he’s embarrassed, he lifts his ass and slides his shorts off the rest of the way, sitting back down on the seat naked from the waist down. He pulls his feet up to rest on the edge of the chair, spreading his legs in the process. Kirishima dives back in right where he left off, nose now brushing against his dusky pink hole.

It’s disgusting, he can’t imagine it smelling especially great down there, but Kirishima The Wolf seems to think otherwise, utterly captivated by the area. He licks, only the tip of his tongue touching the hole while the rest wets his ass cheeks, and Bakugou pushes his snout away. He slides off the chair onto his knees, turning around to rest his elbows on the chair and pushes his ass out. Reaching back with one hand, he pulls on one of his cheeks and a deep moan is ripped from his chest when Kirishima wastes no time going right for his hole.

Fuck, it’s the best thing he’s ever felt in his life, maybe even better than when it was on his cock. Kirishima’s tongue is long and rough, adding a sweet, firm pressure to that delicate ring of muscle, drenching the area in his hot spit. Bakugou gasps and cries out, unable to keep holding back and no longer caring. The more noise he makes, the more excitedly Kirishima licks, growling as he moves his snout from side-to-side, nails clacking on the floor as he shifts closer.

He presses his tongue in deeper and the narrow tip penetrates Bakugou’s entrance. A yelp slips from his mouth and Bakugou bucks his ass backwards into the wet heat, rutting against it as it worms its way further inside him. Kirishima’s licking his insides, his sharp fangs gently digging into his ass cheeks, before pulling back out to lap across the fluttering hole.

Bakugou wants more, he needs more, his thighs are trembling and his dick is leaking onto the floor, unattended and red and desperate for touch. He lays his face onto the chair, his hot cheek squished against the seat, and brings his other hand down to loosely wrap around his length, pumping slowly. He just wants to take the edge off a little, but he’s not ready to come yet. Kirishima’s wolf tongue feels way to incredible not to make it last as long as he can.

“Good boy,” He slurs, and is hardly surprised when he feels drool spill out of his mouth and pool around him on the seat. “Such a good boy.” He murmurs, and the wet warmth leaves his asshole to lick a trail down his taint, nudging against his balls again. He feels soft fur brushing against his taint then, and a hot tongue at the underside of his cock. His eyes slide down to peer between his legs and sees Kirishima there, long snout and dangerous teeth huffing against his crotch, pink tongue darting out to wet him as he lazily strokes himself.

He brings his other hand from his ass down to curl around Kirishima’s flank, petting him in slow, encouraging strokes. “Who’s my good boy.” He croons, and Kirishima pulls back again. He frowns, about to protest, when he sees two big paws fall down on either side of his head, feels a soft warm body press against his back, and something hot and slick rub against his lower back.

Oh shit, oh shit fuck yes.

Bakugou slips out from under Kirishima’s body and scrambles over to his bed, climbing up to lay his top half on the mattress and push his ass out. He looks over his shoulder, excitement thrumming through his veins when he sees the large wolf stare him down. His hackles are raised, teeth bared in a brief snarl, and a red thick dick hangs between his hind legs. It glistens with slick with a bulbous knot near the base and slightly tapered at the head, and Bakugou’s eyelashes flutter, eyes rolling into the back of his head with the surge of arousal that courses through his groin at the image.

“Come here, boy.” He coos, all sense of shame gone, as he pushes his hips back and presents his ass for fucking. Kirishima clambers over, immediately resuming his previous position with front paws on either side of Bakugou’s head, and starts to rut against him. His cock slides against Bakugou's’ crack and his movements are jerky and unrefined, and for a moment Bakugou just enjoys the feeling of his hole being slicked up and rubbed on. But eventually it’s not enough and he can tell Kirishima’s getting impatient too, so he lends a hand. He reaches back to grab at Kirishima’s cock and line it up with his hole, but it’s so wet and slippery he can’t get keep his grip.

“Hold still you fucking mutt.” He scolds quietly, smirking when he hears a whine in response. But Kirishima listens and stills his hips, lets Bakugou guide it to his hole.

As soon as the tip touches the puckered ring, however, Kirishima loses his mind and thrusts in, seating himself half-way in in one single motion.

“Ahh- fuck!” Bakugou chokes, eyes bulging and fingers gripping his sheets, head falling back against the soft fur brushing against his neck. Kirishima’s jaws are parted and panting over his face, his sharp teeth looming over him, towering over him with a threat of violence and dominance that makes Bakugou mewl like a bitch.

“Good boy, good boy, good boy, yes - yes-” He chants mindlessly bordering on a sob as Kirishima starts to hump into him with no regard for his comfort. He doesn’t give Bakugou any time to adjust to the intrusion - the sensation of having his asshole penetrated completely foreign for him - nor did Kirishima give him any preparation besides his tongue, and Bakugou feels tears prick at the corner of his eyes. The stretch burns but it’s so fucking good, and the more he spouts thoughtless praise at the dog fucking his ass open the harder and faster Kirishima pounds into him, his thick wolf cock swelling inside him and spreading Bakugou open deliciously.

Bakugou brings a hand up to pet Kirishima’s soft fur, cock twitching with need where it’s trapped against the mattress, when the wolf leans down to lick up and down his neck, sharp fangs that are even longer than his normal ones carefully closing around Bakugou’s neck. Bakugou squalls pitifully, drool and tears and sweat tracking down his face. It’s freeing in a way Bakugou would have never imagined to feel so powerless in such a strong animal’s jaw, the knowledge that Kirishima could snap his neck or tear his throat out making him lose all sense of coherent thought.

“Fucking - yes - own me!” He cries, “Make me your bitch!”

He feels Kirishima’s answering growl vibrate in his neck and back, and Bakugou turns to face his wolf. Kirishima licks across his lips in his version of a sloppy kiss, and Bakugou drops his jaw to let him lap inside his mouth and across his tongue. It’s so wet and hot, and Bakugou moans into him, imagining sucking him off and feeling that slimy hot cock fill and fuck his mouth.

“Fuck, fuck,” He whispers, strained, into Kirishima’s fangs, “Fuck my ass ‘til I bleed you fucking stupid mutt-” Kirishima cuts him off with a nip to his face, missing Bakugou’s nose by millimeters. He growls deep and menacing, and slams his cock in balls deep, hitting a spot inside Bakugou that makes a spark of electricity shoot up his spine. He chokes on his spit and arches his back, chasing after it.

“Right there! Yes-! Good boy, such a good boy~” Gasping with each thrust, he pets the soft fur of Kirishima’s strong flank and lets him lick up and down his neck, nuzzling at the back of his ear. “Mmmm fuck my ass just like that-” He’s cut off by a brutal thrust, Kirishima’s hips pistoning in and out of him at an inhumanly fast pace, animalistic and raw in its ferocity. Every thrust scrapes against his prostate and Bakugou feels drool slip out of his mouth, Kirishima crooking over to clean it off with his tongue.

And then his rim feels like it’s being split open, stretching and burning and it feels like Kirishima’s cock is getting even thicker but how could that be - and then Bakugou remembers how wolves knot when they come, and he lets out a sob. He arches his back and spreads his legs to accommodate the new girth, his own cock being pressed and rubbed against the soft sheets, just barely enough friction to get him off.

But it is enough, and when he feels slick warmth squirt all over his insides, he comes untouched with a shout. His jizz splatters against the mattress and his own belly, his stretched hole clenching around the thickening intrusion. God he feels so fucking good, so full and hot to have his guts stuffed with dog cum.

He brings a shaky hand to probe at his lower belly, almost sure there will be a bulge there with how full he feels right now. Kirishima’s still working his knot inside him in shallow little thrusts, grinding his soft furry hind legs against Bakugou’s ass. It feels so weird but it makes him hot all over and a shiver ripples down his spine. He tries to pull away but finds he’s stuck. Kirishima lets out a little whine at that, clamping his jaw over the back of Bakugou’s neck once more to hold him still.

Kirishima really did make him his bitch.

Now that the sex haze has stopped clouding his mind a bit, Bakugou shifts on his knees and realizes how sticky and gross he feels. He can feel the cum clogging up his ass and he’s covered in sweat and wolf fur. He runs his tongue over his teeth and shudders at the memory of letting Kirishima lick inside his mouth, but when he feels the teeth at his neck nip lightly and his softening cock give a final interested twitch, a sinking, heavy feeling settles in his gut.

His face burns with shame at how willingly he bent over for Kirishima. But Kirishima’s soothing licks against his nape and shoulders lull him into a comfortable state of drowsiness and he stops thinking. They stay that way for a while - close to twenty minutes by Bakugou’s estimate, but it could have been longer or shorter for all he knows.

By the time Kirishima’s cock has deflated enough to slip out of him, he’s almost fallen asleep. It’s only the hesitant lick against his loosened hole that alerts Bakugou to the separation, and with aching knees he pulls himself up the rest of the way onto the mattress, rolling over onto his
back.

“Fuck, my ass is gonna be sore tomorrow.” He groans, bringing a hand down to palm at his hole and slipping a finger in to feel how worked open it is. It slides in easily and a gush of jizz dribbles out, getting all over his finger and the sheets.

Kirishima makes a sort of quiet yap and drops his head on the bed next to Bakugou, his tail swishing in a relaxed manner.

“I’ve never done that before.” Bakugou adds quietly, and the twitch in Kirishima’s ears lets him know he's heard. When he glances over at him his fluffy tail wags harder, tongue poking out to lick over his own snout. Even though he can't speak, Bakugou can imagine his voice, his eyes still so expressive and honest even in lupine form.

“You ever tell anyone about this, and I’ll fucking kill you.”

Kirishima doesn’t say anything - he can’t, of course - but his eyes seem to shine with understanding, and he brings his head forward to give a tiny lick on Bakugou’s forearm. Sighing, he scoots over and pats the side of the bed.

“Get up here already.”

Kirishima perks up and leaps onto the bed, stretching his hind legs out behind him and laying his head on Bakugou’s lap, letting out a contented wheeze. Bakugou curls a hand into his soft fur, stroking him slowly, and wonders what the hell he’s going to say when Kirishima turns back to normal.