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Izuku’s asshole hurt.
It had been weeks of almost non-stop sex, and Izuku wasn’t sure how much more he could physically take. He was exhausted, Katsuki was exhausted, and they were beginning to lose hope. No matter what they did, the rut would come back a few hours later, leaving Katsuki helplessly horny, driven frustratingly, painfully mad with the need to seek release.
Both of them were beginning to find it a bit ridiculous. Katsuki had been tight-lipped about his rut at first, leaving Izuku to research werewolf mating rituals in secret at Professor Yagi’s private library. His research told Izuku that what was going on with Katsuki's rut was most certainly out of the norm.
Ruts followed a seasonal schedule—every spring, for under a week at most, Katsuki was supposed to allow his body to release its inborn wolf desire to breed before the winter returned, while his fertility was at a yearly high. Once those few days of rut where over, Katsuki would return to normal, giving Izuku’s poor body a break until the next mating season came around.
Ideally, that would be the case. But their current situation was most certainly not.
Katsuki was constantly in a bad mood. Torn between being needy to the point of aggressive, whiny desperation, and overstimulated exhaustion, he wasn’t satisfied no matter what the two had tried, and they had tried just about everything.
Izuku knew to prepare himself for Katsuki’s rut. His questionable internet researching abilities had come in handy for once, and he had found an online forum of humans dating werewolves—and he was fairly certain they were actual werewolves and not just furries this time.
He’d read what the human partners had to say about experiencing ruts with their werewolf beaus thoroughly, and was ashamed to admit he’d even read some Twilight fanfiction for further inspiration.
But his embarrassing research had paid off. At the beginning of his rut, Katsuki seemed to be enjoying himself just fine, and Izuku would admit that he enjoyed a fair bit himself. Excitement at experiencing his and Katsuki’s first rut had him rebounding quickly, and despite how hard it was on his body, Izuku was perfectly happy to assist his Kacchan through it.
When the rut reached day 8, Izuku had questioned Katsuki about when it would end, definitely tiring, but still basking in the honeymoon-like week he had spent with his partner. Katsuki had grudgingly explained that he didn't know either, every werewolf’s cycle was different.
“Oh!” Izuku gasped in understanding. “Like how girls and people menstruate for different lengths of time, right?”
After being forced to swear he would never compare Katsuki’s rut to a period again, Katsuki had reluctantly admitted that he didn’t know why it was dragging out so long, but that it would probably end soon.
It didn’t end soon.
They kept at it, trying over and over. Katsuki became more and more cranky and sullen from his constant, insatiable need, while Izuku became more and more exhausted, his body not built for even a few days of Katsuki’s rut, never mind weeks of it.
There was nothing that seemed to work. Regular sex, any way they did it, calmed Katsuki down for a few hours, giving them just enough time to bathe, eat, and begin to really feel the ache in their strained muscles, before Katsuki was back to his wild needy frustration. Scratching himself, picking fights with the pizza delivery man, scratching the refrigerator door, it was only a matter of time before he couldn't resist the urge to just jump Izuku and mount him.
They’d never gotten more use of their sex toys, and that said something considering they used them regularly. Katsuki had barely spent a moment without something plugging him, that extra edge helping him achieve orgasm quicker as he fucked into Izuku, or with some gentle vibrations in him while Izuku rode him, milking him until he was raw and sensitive. And yet he was still aching for more, the part deep inside—literally, but more pressingly, metaphorically—screaming for attention, for more, more, more.
It wasn't long before they realized that simply holding out was not going to work. Izuku eventually came to the conclusion that despite the humiliation it would put them through, he needed to ask for help.
He had done all the research he could himself—not even Twilight fics were able to provide a clue as to what Katsuki was going through. Izuku was out of ideas, and, desperate and exhausted, he turned to Professor Yagi, the only resident expert on the Supernaturals he could think to ask for help.
Known infamously throughout the country as the one keeping the peace between the non-humans, Yagi had dealt with rogue vampire clans killing towns of humans, sirens luring fishermen to their demise, and spats between the undead and the living. He’d mediated were-creature disputes over land and territory, and used his power as a human-turned-demigod to ensure the peace between creatures of every sort. He prided himself in his ability to find a solution to every supernatural conflict.
But this was the one human-supernatural issue Yagi thought he couldn't resolve.
It took him a while to catch his breath, having choked on the blood he spat out at the sheer detail Izuku had presented him with regarding his beau's mating issues—entirely unsolicited and perhaps a bit scarring if you asked him. When he did manage to heave a weary sigh, he decided to do the one thing that in all his years as the peacekeeper between supernatural beings and humans, he had never had to resort to:
Shoving the responsibility at his old mentor, and running away.
"Sorry, my boy!" Yagi apologized, grabbing Izuku's hands with his clammy ones, and pressing a small slip of paper into them. "I fear this is an issue not even I as the retiring Peacekeeper of the nation can resolve. The only one who can possibly deal with so disturbing—er, sensitive a matter is my mentor himself, a man much better suited to answering your questions about how much ejaculate your werewolf boyfriend should be producing than I am. Call him and let him know I sent you. Now, if you'd excuse me, my boy, I must be on my way to help the fae watch grass grow!" Yagi turned tail and fled.
Izuku blinked at the card he’d been handed by his mentoring professor, the protector of humans and supernaturals alike, the brave godlike figure known to never back down from a foe or challenge—alternately known as the man choking on his own bloody spit as he scampered away. This was the card of Professor Yagi's own teacher himself? What kind of a man could have mentored a demigod, Izuku wondered in awe.
Reading the card over curiously, he found an address and a phone number, and the title ‘Dr. Gran Torino’. After skimming the contents on the backside, he pulled out his phone and immediately dialled the number.
Doctors well-versed in supernatural biology existed?! Why hadn’t Izuku been told of this before?!
It didn’t take Izuku long to set up an appointment, though the grumpy old receptionist was a bit off-putting.
He headed home not long after, a spark of hope in him, and it wasn’t even dulled by the sight of Katsuki mounting and humping the sofa armrest greeting him when he returned. It would only be a day before they could get him checked out by the doctor who mentored Professor Yagi.
Izuku inhaled slowly when Katsuki pulled out an alphabetically arranged box of dead squirrels to haughtily present to Izuku, evidently proud of his mating gift. Only a day longer, Izuku reminded himself, thanking Katsuki for the absolutely delightful gift, wondering when the earliest he could throw it out was.
The train ride to the doctor’s office was tense from the start.
Izuku eyed Katsuki worriedly as they hurried through the station, hearing his werewolf boyfriend grind his teeth in anger, visibly seething when a stranger ended up a little too close to Izuku for comfort.
Izuku was sure it was just an accident, but Katsuki was ready to throw hands. So Izuku grabbed them before he could do so, squeezing them reassuringly between his until he felt Katsuki's claws retract.
The moment Izuku thought things might be okay, a frog-girl stumbled into Izuku's chest. Katsuki would have tried to either rip her tongue out with his bare hands or perhaps mount Izuku right on the floor of the train station to lay claim to Izuku, had it not been for Izuku dragging him into a washroom stall and pulling his pants down right there.
“I’ll probably have to get my wrist checked out too,” Izuku muttered forlornly, stretching his aching wrist. Katsuki just scowled harder, bodily shoving Izuku even harder against the train doors, covering Izuku’s body with his as he shoved his face into Izuku’s neck, tail wagging in warning behind him. Izuku closed his eyes, ignoring the affronted stares of the people around them, taking a deep breath.
It was just easier to pretend Katsuki wasn’t humping him, right there in public on the train.
“I thought I did a good job milking you dry,” he sighed, disappointed, ignoring Katsuki’s responding growl. “Wouldn’t it be funny if I got carpals from jerking you off so much?”
Katsuki panted loudly in Izuku’s ear, nails extending as he grabbed at Izuku’s back.
Izuku swatted Katsuki’s hands away. “Kacchan!” he whined quietly. ”Don’t rip my new jacket. I’m not buying another .”
He tuned out Katsuki’s whining and growling, affectionately but exasperatedly sighing. Izuku loved sex with Katsuki. He took great care to make his boyfriend feel good, even when it meant he had to spend the past few weeks walking with a limp, dick sensitive and aching in his pants. But having to buy a sixth jacket in one month was too far. In fact, he was sick of all his clothing being destroyed. Izuku would rather Katsuki try to destroy his ass rather than another good pair of jeans, he thought with a sigh.
With the way Katsuki was growling, Izuku thought that might happen in a few minutes anyways.
Despite Katsuki ceaselessly trying to lay claim on Izuku, they managed to arrive at the doctor’s place without any major incidents, like being written up for public indecency.
The run-down building was on the edge of the town was imposing and eerie, but Izuku double checked—they were at the right place.
Tentatively entering the silent, creaky office with a sulking Katsuki behind him, still unsatisfied that Izuku only gave him a handjob in the train station washrooms, Izuku was startled by the sudden appearance of white wings.
Izuku’s yelp of surprise made Katsuki growl, pushing Izuku behind him and posturing aggressively. The wings twitched in annoyance.
Izuku was quick to wrap his arms around Katsuki. “Kacchan,” he soothed, rubbing a hand down his tense boyfriend’s side.
Katsuki slowly calmed down, relaxing when Izuku mimicked the scenting motion Katsuki frequently did. He wasn’t sure what glands or what hormones stimulated whatever it was that calmed Katsuki down, but it was effective in calming him down.
Finally able to focus on the owner of the wings, Izuku was surprised to see a tiny old man with grey hair, just a shade or two darker than his wings. Izuku examined the spread of feathers. A cherub?! The odds of being in the presence of such a holy being were infinitesimally small. He gaped at the small man, his surprise only rising when he saw the annoyed look on the man's face. Cherubs were supposed to be angelic, weren't they?
“Why the hell are you whippersnappers eight minutes late?” He snapped his wings out, lifting himself off the ground as he scowled. Izuku gulped. Maybe he wasn’t as angelic as he seemed.
“Three weeks?”
Izuku winced in the creaky chair facing the doctor, exhausted just by the memory of the past three weeks. “Um. Yeah.” His eyes flickered to Katsuki, taking in his cross-armed, stiff posture, pressed against Izuku’s side. He had on a glare as usual, but Izuku could tell it was just an uncomfortable one. Izuku’s face softened, and he placed an arm on Katsuki’s thigh.
Katsuki visibly jumped at the touch, body on alert, and Izuku watched his slow inhale as he tried to calm down.
Of course Katsuki would be on edge. He was a werewolf in rut, it was incredibly hard for him to behave normally in public like this.
It was customary, as most would assume, for the wolves and their partner of choice to spend their mating cycles locked up in some room or the other, having at it until the need to breed had passed. With so long of not being able to satisfy that urge, his already hormonal boyfriend was on an even shorter leash.
Dr. Gran Torino blinked at them consideringly, wings folded in behind him as he tapped a pen against his clipboard. “Young ones really go at it nowadays, don’t they?” Izuku flushed. “Reminds me of when I was younger, the other cherubs had another thing coming for them, hah!”
Izuku grimaced. Dr Torino rolled his eyes at the human's clear disgust. Gran Torino wasn't interested in hearing about his student's students' sex lives, but here he was anyways.
“Tell me, human,” Dr Torino nodded at Izuku. Izuku sat straight, listening closely. “How long have you two been dating?”
“Oh.” Izuku blinked. “I think, like two years and some? Maybe a bit longer—”
“Two years, 6 months, 18 days.” Katsuki looked cross, a firm pout on his lips. Izuku’s gave him a fond look, squeezing Katsuki’s thigh. Katsuki ignoring him but leaned in just a bit.
Dr Torino was not amused. He rolled his eyes at the display of puppy love. “And he hasn’t had a rut with you before this?”
“Ah!” Izuku sat up. “Last year I had an internship with Professor Yagi’s chief of operations between the humans and the clan of Nymphs near the—”
“Spare me the details boy,” Dr Torino rubbed the space between his brows. He wasn't interested in hearing yet another rant about supernatural creatures. The intrusive questions about his cherub wings and the supernatural biology posters on his walls had been bad enough. “You weren’t with him during the rut?”
“No,” Izuku said sheepishly, sending Katsuki an apologetic look. “I—er, wanted to be, but Kacchan said he was fine, so I took on the internship.”
Dr Torino sighed. “Alright. It’s clear what’s going on.”
Both Izuku and Katsuki sat up straight.
Dr Torino was unconcerned, ruffling through some papers, which Izuku wasn’t sure was a good thing or bad thing. Was all hope lost? Did Kacchan have a fatal condition? Was he going to nut so hard he exploded? He paled.
Katsuki didn’t have to be neutered, right? Did domesticated werewolves have to get neutered? Izuku snapped out of his muttering when the doctor snapped his wings open irritably, trying to get Izuku's attention.
“He’s a werewolf in a homosexual relationship. His body knows he has a partner but hasn’t caught on that he doesn’t have a female partner.” Dr Torino gestured at Katsuki vaguely.
Izuku frowned. “...So that means...?”
“It means his body needs to be made to understand that the conditions are different than what it’s expecting.” Izuku stared blankly. “He needs to be sufficiently convinced out of his rut,” Dr Torino said with a sigh.
Izuku nodded pensively, but Katsuki leaped out of his chair, growling.
“I do not need to be bitched! ” he bared his fangs at Torino, who gave him another sigh. Izuku got up worriedly, seeing Katsuki’s claws extend and his tail stand up, ears pointed in a clear sign of aggression. “Fuck this shit!” Katsuki growled. “It’ll end on its own, I don’t need to be bitched! Fuck you, ‘M not gonna listen to this bullshit!”
Izuku yelped. “Kacchan, your health card! We need to fill the paperwork—”
Katsuki slammed the door behind him as he stormed out of the makeshift clinic. Izuku stared at the door, worried, not deeming it safe to let his currently very hormonal boyfriend run around alone, but he saw—and heard—Katsuki’s frame loitering nearby outside. The faint shadow he was casting under the floor was stomping and growling around, so Izuku anxiously turned back to the doctor.
Dr Torino just rolled his eyes, handing Izuku the paperwork.
Izuku bit his lip, mind wandering as he filled out the form. When he finished, he hesitated before handing it back. “Do you think it will… help him?” he asked quietly as Dr Torino reached for their paperwork.
Dr Torino didn’t blink, hand freezing where it was about to grab the papers. “Almost certainly.”
Izuku chewed his lip for a moment, eyes flickering to the where Katsuki’s shadow was visible under the door, before putting the papers back down on his lap. “Can you… tell me more about this ‘bitching’ thing?”
To no one’s surprise, Katsuki’s rut didn’t, in fact, just conveniently end because he threw a tantrum at the doctor's office.
It was only after another two days of letting Katsuki have his way that Izuku was able to enact the plan. He could feel the effects of the medication Dr Torino prescribed, and even waiting another half day was too much to bear. Any longer, and he didn’t think he’d even be able to walk with the pain of walking with such big, heavy, stuffed nuts. He didn't even know his balls could get that big, physically.
Izuku looked down at his lap, eyes lingering on where the outline of his expanded balls was visible through his boxers, before flitting to the bag under the bed, the contents inside already prepped and ready to be used. Everything was ready, all he had to do was convince Katsuki into it.
Doctor Torino had some interesting information for Izuku after he asked for further information on how to bitch Katsuki.
“You’re going to have to do what he’s done to you, only overpower him, and make him submit,” Doctor Torino had summarized, flippant and unconcerned. “He’s likely going to put up a fight, so it’s not a recommended course of action if there’s a concern of genuine discomfort or a lack of established boundaries in the sense of bedroom activities—”
“Ah,” Izuku blushed, interrupting. “That’s-uh. It-it won’t be a p...problem.”
His face heated, and he ducked his head down, refusing to meet the Doctor’s eyes.
How could he explain to Professor Yagi’s mentor that he and Katsuki had a very kinky sex life and already had established safe words for any sexual activities they might want to spring on another? Or that he knew exactly how much Katsuki loved being pushed down and taken full advantage of, even—especially— when he put up a fight?
“...Kids these days,” Dr Torino muttered under his breath, shaking his head. Izuku flushed harder, but when he glanced up, Dr Torino looked almost amused.
“In any case, you’re going to have to use a few things to supplement the process,” Dr Torino pulled out a pad of different prescription paper. Izuku peered at it, cocking his head curiously as the doctor scribbled away.
“You’re going to need these to enhance your drive and this will help your —” Dr Torino made a crude motion with his hands, and Izuku instinctively yelped, covering his face. He peered between his fingers, seeing the old man snickering at him. Izuku resisted an embarrassed huff, face burning.
“Werewolves are highly sensitive to hormonal levels,” Dr Torino’s voice turned serious. “You’re going to have to take these for a few days, and then space out the last two by two days so that you don’t get addicted. They’ll increase your sex drive, and more importantly, your ejaculate. I’m sure you’re well aware of the sheer volume that is produced during a rut,” Dr Torino’s dry voice held a hint of amusement when Izuku’s face heated again. “You’re going to have to produce at least that much. Two or three days after taking this, you should be set to initiate the bitching process.”
Izuku bounced his legs, hands gripping the edge of the mattress. He was thrumming with anxiety and felt built up. It was driving him mad. The medication had him antsy since he first took it, but after two and a half days, when he knew he could finally touch Katsuki, well, despite his 100% human nature Izuku felt like he was going to sprout claws and fangs and absolutely demolish anything that tried to get in his way to his Kacchan. Even—especially—the bathroom door.
If this was only a fraction of what rut was like, Izuku couldn't comprehend how Katsuki had managed this long.
Izuku was filled with a renewed love and appreciation for his boyfriend. Even when he was being driven absolutely mad by his supernatural biology, he did his best to not inconvenience Izuku and only destroyed two doors in his entire rut. Izuku was about to destroy his second and he wasn’t even technically in rut. Only an artificially stimulated, temporary one.
Izuku simply couldn’t wait to get Katsuki’s ass. How long was he going to take in the shower? Should he go help him out? He could scrub Katsuki’s body, lather him in soaps, press kisses to his muscles, down his back, to the inside of his thighs, between his thighs…
Or even better, he could help dry Katsuki off, wrap him up in towels all over, keeping him tucked in and cozy against Izuku, make sure every part of him was dry before he got wet again.
Izuku could rub—lick—the water off his rippling abs, give his delicious, firm but tender chest a gentle massage while he was at it. In fact, he could go and get up right then and there, find Katsuki, push him up against the wall—
No. Izuku couldn’t just barge into Katsuki’s shower and try to fuck him there. Sure, Katsuki had done that to him repeatedly, but... He forced himself to take a deep breath in and out, trying to calm down.
He just had to wait until Katsuki was done. Katsuki wasn’t going to take much longer, probably, hopefully, Izuku just had to wait. Wait. Wait. He leapt off the bed when the shower turned off, the signal that Katsuki had finished driving Izuku’s heart racing as he fought the urge to race to the door.
It took Izuku a long moment to force himself to sit back down, and he held his breath until he was lightheaded, trying to calm down.
Izuku had never been more thankful he was human. Rut was hell.
It took a long time—painfully too long, really—for Katsuki to leave the washroom. Katsuki’s brows were crossed in his discomfort, the next wave of his rut already arriving. He was shirtless, a small towel lazily draped around his shoulder, another one snug around his hips. Izuku’s jaw dropped slightly. Even after all this time, the sight of his beautiful werewolf beau made him lose his breath.
Katsuki had the most beautiful body Izuku could ever imagine. Abs rippling, body firm with visible muscles as he dried off his hair, he was perfect. Anyone could see how undeniably strong he was, but his desk job as a chemist had an impact on him, and there was just enough softness to his frame to make him the best possible size to cuddle with. And he was cuddly, especially after sex, Izuku thought absently, mouth watering as he stared. He wanted to bite and mark and kiss everywhere.
He would have flushed at the sheer horny energy of his thoughts if he wasn’t so shameless from the all-consuming desire he had for Katsuki—a normally present part of his life, for sure, but it was enhanced a fair bit due to the hormone pills.
It was nice to know that Katsuki, at least, felt similarly. Izuku licked his lips, gaze turning sultry as he looked Katsuki up and down, resting his hand on the bruises Katsuki had sucked into his thighs only the night before.
Katsuki was obviously horny. But coming out of the shower to see Izuku nearly vibrating with energy on the bed, naked save his boxers, displaying the multitude of marks over him made Katsuki suspicious enough to halt his overwhelming need to breed to glare suspiciously at his lover.
He sniffed the air warily, eyes narrowing at Izuku’s frame. Izuku smiled nervously, beckoning Katsuki closer.
“Kacchan,” he said, trying to make his voice sound normal. From the way Katsuki’s eyes flashed for a second and his wolf ears went from sitting flat on his head to straight up, at attention, Izuku failed at hiding his desire.
But when Katsuki came over, folding the towel that was draped over his shoulders, to stand before Izuku, Izuku didn’t regret it, spreading his legs and reaching out to wrap his arms around Katsuki’s waist, pressing his face against his Kacchan’s stomach.
Katsuki’s waist was so small, Izuku thought in heady awe. He’d always loved it, it was the absolute perfect size for wrapping his arms around when they spooned, but he had never realized just how perfect it was to grip as he thrust into Katsuki.
Izuku couldn’t wait to leave bruises of his fingerprints all over Katsuki’s hips, to press in his nails until Katsuki was covered in his scratches, bites, his marks, marks showing that Katsuki was his—
Izuku took in a deep breath, face pressed against Katsuki’s skin, cooled by the air after his shower, but quickly warming.
Katsuki’s werewolf biology caused his body temperature to normally be a few degrees higher than Izuku’s, leaving him a walking furnace, but there was nothing warmer than the tight, wet caverns of his hole. Katsuki would clench around him so tightly when Izuku pulled his nipples roughly, and the heat around him would become almost too much to bear, leaving Izuku helpless to buck his hips into his lover, as he wanted to at that very moment—
“Kacchan,” Izuku purred. Quickly clearing his throat, he continued. “Kacchan. How are you feeling?”
Katsuki grunted, shifting in Izuku’s arms, tail jerking and moving the towel around his hips slightly. Looking down, Izuku saw Katsuki’s growing erection.
Katsuki’s silence was odd, and Izuku looked up, momentarily distracted from his pure horny ‘must fuck Kacchan’ thoughts to see what was causing the uncustomary silence from his lover.
But Katsuki refused to make eye contact, his face pinched, strained not only by his erection but—Izuku frowned—regret, almost a sense of shame.
Izuku gave Katsuki’s waist a quick, soft squeeze. “Kacchan?”
Katsuki grunted. “What.”
Izuku continued to stare up at him, but Katsuki refused to meet his eyes. Izuku leaned forward, pressing his lips to Katsuki’s stomach and letting them linger there for a long moment. “Kacchan? What’s wrong?”
“Nothing.” Sensing Izuku’s clear disbelief, he scowled lightly, meeting Izuku’s eyes briefly before turning his head away. “I’m fine for another few hours, so fuck off, Deku.”
“Clearly you’re not,” Izuku pointed out, pressing a hand to Katsuki’s prominent bulge.
Katsuki ripped out of Izuku’s embrace, swatting Izuku’s hands off him and taking two steps back, hands grabbing at his towel, keeping it up.
Izuku was on his feet in an instant, face concerned. Why was Katsuki refusing his touch like that? He’d wanted nothing but to get closer for the past three weeks. “Kacchan?"
“I said I’m fine,” Katsuki growled, teeth coming out instinctively, a low, threatening rumble echoing in his throat.
Izuku wasn’t afraid or put off. It had been years since he had feared Katsuki’s instinctive, aggressive wolf behaviour. Instead, he stepped closer, hands out and low, showing his hostile, vigilant boyfriend he meant no harm.
Izuku moved closer slowly, not deterred by the growls he got. When he was close to Katsuki, who had pressed himself up against the opposite wall of the room, he noticed Katsuki digging his fingers into the palm of his hands, the small bloody indents unable to heal with the way he was continuously digging into them.
“Kacchan!” Izuku grabbed Katsuki’s hands, forcing him to stop hurting himself. “What’s going on?! Why are you—?”
“Deku, stay away.” The demand was shallow. Izuku squeezed Katsuki’s wrist. Katsuki let out an angered whine, voice almost pleading as he ripped his hands away from Izuku’s grasp. “I’m trying to hold back, so just fucking back off for once in your life, will you?!”
“You don’t need to hold back,” Izuku soothed, trying to pull Katsuki close, but Katsuki pressed himself into the wall, swatting Izuku’s hand away again.
“Don’t fucking lie to me,” Katsuki snarled. “You’re fucking exhausted. You're covered in marks everywhere—you look like I fucking mauled you." Katsuki's voice broke slightly, his guilt obvious. "This shitty rut will go away on its own. I’ll deal with it myself, this isn’t your problem, Deku, you're just a human. You don’t have to fucking—”
“Kacchan.” Katsuki’s head shot up, immediately alert. That firm, upset tone of voice was rare from Izuku, and he couldn’t help his panicked response. Izuku very, very rarely was so cruel as to call him a bad boy or anything, but the mere tone of voice was enough to make Katsuki feel small.
“Kacchan,” Izuku’s voice softened, seeing he startled his already on-edge partner. He hesitated when Katsuki suppressed a flinch, but pressed himself up against Katsuki, pinning him bodily against the wall. Izuku was assured that he was doing the right thing when Katsuki let out the smallest of whines at the touch, a desperate, frustrated, pleading noise that hit Izuku right in the chest. And dick.
“Thank you for trying to be considerate of me,” Izuku murmured, hand reaching out to pet Katsuki’s ears, the soft appendages standing stiffly upright his nerves.
Katsuki flinched, trying to hold back from leaning into the touch, but Izuku continued to pet him. Katsuki’s teeth were bared, and Izuku caught the hints of his tail wagging under the towel, wisps of the fur brushing against Izuku’s bare legs.
“But you don’t have to go through this alone,” he cooed. “Yes, I’m a bit tired, but so are you. And just because I'm human doesn’t mean I can’t be here for you. I know you can do it alone, but Kacchan, I’m your mate."
The hand not petting Katsuki’s head slipped into the back of Katsuki’s towel and grabbed the base of Katsuki’s tail.
"Let me take care of you, Kacchan."
Katsuki shuddered, and the towel, already loosened around his hips, fell to the floor, exposing his leaking erection.
Izuku leaned back, taking the sight of his werewolf beau.
Exhausted by the nonstop rut, Katsuki leant his back against the wall, eyes squeezed shut as Izuku continued to pet him. Katsuki’s body was covered in only a fraction of the marks of Izuku, but Izuku was determined to change that by the end of the day. Katsuki’s dick stood ripe to attention, the tip already leaking pearlescent fluid.
Izuku licked his lips. He wasn’t a wolf himself, but that was one boner he would love to have in his mouth any day.
Katsuki must have been painfully hard, Izuku thought in pity, taking in the blue tint of his balls. Every vein in his length popped out noticeably, and his balls were pulled in tight, his tip leaking clear fluid.
It didn’t take long for Katsuki to start bucking his hips up against the air, desperate for any friction, any touch, any pressure to ease the pain, but yet he still tried to push Izuku away, not wanting to exhaust his human lover.
Izuku leaned down and pressed a kiss to the tip of Katsuki’s dick, a silent thank you for Katsuki’s consideration. He would have appreciated it a few days ago, but now?
Izuku was going to be the one exhausting Katsuki.
Katsuki’s hips jerked into the touch, a strained groan escaping him, nails extending as he fisted his hands, trying to hold back from grabbing Izuku’s head and mouth-fucking him until he choked.
One hand firmly gripping the base of Katsuki’s tail, he led Katsuki to their bed.
“Let me take care of you, Kacchan,” he repeated, voice quiet but ringing with confidence.
Izuku knew what he had in store for Katsuki was going to make Katsuki feel much better immediately. He just needed to show Katsuki that, despite his protests.
Katsuki looked like he wanted to argue, but Izuku squeezed the base of his tail, and he shuddered, body tense but pliant under Izuku’s touch.
Izuku pushed Katsuki down, and Katsuki, exhausted and willing, let himself be arranged on the bed until his head was resting against the pillows, on his back with legs spread, Izuku leaning between them.
Izuku felt his own erection throbbing in his boxers, weeping for attention, but he wanted to please his partner first. Katsuki was doing his best, he was being so obedient, he had to reward his good boy.
He dipped his head, taking Katsuki’s throbbing length into his mouth as deep as he could. Katsuki threw his head back, gasping as his sensitive flesh was engulfed by the wet caverns of Izuku’s mouth. Izuku pulled no punches, sucking long and deep, humming lightly, knowing how that drove his boyfriend crazy. Katsuki was futilely attempting to keep his voice down, his grunts and groans, little purrs and growls escaping him as he writhed on the bed below Izuku.
But Izuku wanted to hear him loud and unrestrained. He flicked his tongue against the tip, alternating between little teasing licks and long, broad ones as he pumped Katsuki’s shaft with both hands. When Katsuki was finally whining, the wanton, unabashed noises echoing in their room, Izuku took him deep inside, holding his breath to take Katsuki as long and hard as he could, before pulling off to swirl his tongue around the tip playfully, loving the frustrated, desperate way Katsuki’s claws scratched at the bed-sheets.
It only took a few repetitions before Katsuki was spreading his legs wide, hips bucking as his back arched off the mattress, wanting nothing more than to press further into Izuku’s mouth, but trying to follow the unspoken rules and keep still.
Izuku couldn’t help a smile. Katsuki was still trying to be considerate of Izuku, but it really just made him obedient. It was so cute, even if he felt horrible for his poor boyfriend suffering like that.
He couldn’t help it—it was just so exciting to see his normally composed ‘I’m a big bad werewolf grr I’ll bite you’ boyfriend writhing beneath him during his rut, the one time of the year it was perfectly excusable for him to behave like an untamed beast.
Instead of forcing Izuku down and having his delicious, wicked way with him, as he had so many times during the past while, he was clutching the sheets and whimpering as he desperately tried to keep his hips still, quiet sobs escaping him in his frustration.
Figuring he had teased his poor boyfriend enough—for now—Izuku turned his attention to the empty hole between Katsuki’s spread legs. He picked up the lube he had set out earlier, pushing Katsuki’s hips down to give him better access to Katsuki’s cute little pucker.
Izuku placed Katsuki’s legs over his shoulders as he licked Katsuki’s hole, emphatic and eager. He dragged his tongue all over, sloppy and slick as he wet the area with his saliva before he pressed his tongue as far as he could.
Katsuki’s quiet pants and moans were a symphony Izuku adored as he jerked his boyfriend off lazily as he lubed up his fingers, tongue fucking him as hard as deep as he could.
He would have loved to eat Katsuki out for hours, as he had done many times before, but Izuku knew it would be too mean for him to tease Katsuki for too long, and decided he’d pick up the pace.
Pressing two fingers off the bat was easy. Izuku wasn’t even surprised to find such little resistance when he slipped in the third.
Katsuki was no stranger to the pleasure of anal by any stretch—and he hadn’t been since they first addressed their ridiculously high levels of sexual tension back in high school. Even during his rut, he was fully accustomed to—desired, if you asked Izuku—taking something in his ass. He had spent the majority of his rut with something in his ass, whether it was Izuku’s dick as he was jerked off with a fleshlight, or a toy as he fucked into Izuku.
So it was only when Izuku pressed in the fourth finger that Katsuki tensed, grasping at the bed-sheets, panting loud in their quiet room. Izuku didn’t hesitate, knowing Katsuki’s limits from experience, and knowing that Katsuki knew his limits too, and would signal if anything got to be too much.
It was with that thought in mind that Izuku slipped his fingers out of Katsuki’s stretched hole, and shoved his boxers down. Grabbing his aching dick, he only barely resisted the urge to stroke himself at least to get the maddening edge off, instead pressing the tip against Katsuki’s wet hole.
When Katsuki heard the sound of the lube bottle popping shut, he peered up at Izuku from under the arm he’d thrown over his face, almost innocently confused.
Katsuki’s eyes swept left and right, but he didn’t see any fleshlight or vibrator or any other toy for his aching cock, and he only got to scrunch his brow in confusion before Izuku pressed in, unforgiving in his tempo from the start.
Katsuki gasped, head tossed back into the pillows as his back arched. His eyes fluttered shut, the feeling of being so full so satisfying. Izuku wasn’t holding back, and Katsuki didn’t get a chance to savour the first slide in before Izuku was ramming so deep into him his eyes rolled back into his head in sheer ecstasy and bliss.
Fuck, that felt good.
Izuku generally felt different today, Katsuki thought. He smelt different. Katsuki didn’t know what the difference was, but his nose had been fully cleared by the steam in the shower and he did notice a distinct difference in the scent.
It was good, in a weird way. It was Izuku’s natural scent he was attracted to—that was the scent that had drawn him in since he was just a young pup, the scent that frustratingly made his life revolve around some stupid shitty green-eyed nerd of a human he thought he should have no interest in. But his attraction had been undeniable.
Just like how it was undeniable that whatever there was that was different about Izuku’s scent, it made Katsuki want to spread his legs further, wider, wrap them around Izuku’s waist, pulling him in further, deeper.
Izuku paused when he bottomed out, closing his eyes, nearly overwhelmed with the desire to fuck into the hot, wet heat encasing his dick, as he tried to recall the doctor’s instructions. This gave Katsuki a moment of pause as well.
Izuku smelt so damn good—so delicious. Katsuki’s canines ached, and he could feel his mouth watering in pure desire. Izuku’s scent was dangerous. He was feeling heady and flushed and he hadn’t even scented Izuku yet. The scent alone made him want to spread his legs further, go limp, press himself into the sheets below Izuku, close his eyes, and let Izuku take him.
But there was a part of him screaming not to.
He was a werewolf in rut, not a bitch in heat. He shouldn’t want this, he thought as Izuku pulled out slowly. This was wrong.
Izuku slammed back inside.
There’s never been anything more right than this, Katsuki thought hazily in pleasure. He blinked, confused by the thought. Wait, why was he on his back getting fucked like this? He was supposed to be fucking Izuku, his rut wouldn’t end until he popped his knot, so even if it felt good Izuku was just tiring them out, they should just—
Izuku saw the confusion on Katsuki’s face. Clearly he wasn't doing his job right if Katsuki was able to have any rational thought left in his head. He had to make Katsuki let go, let him enjoy himself. Picking Katsuki’s legs up, he pulled the knees over his shoulders, leaving him face to face with Katsuki when he leaned in, stretching Katsuki’s legs to give clear access to his ass.
Izuku thrust out fully before slamming in, pace unforgiving. His hips slammed in and out, enlarged balls slapping Katsuki’s behind with loud smack with every jerk of his hips. He grabbed Katsuki’s thighs and pressed them as far back as he could, pushing Katsuki’s flexible body to its limits.
Katsuki protested weakly, confusedly, but Izuku just pinned his knees to the bed, legs spread eagle.
It was almost humiliatingly exposing, and Katsuki would protest during normal sex to being presented this way, but during his rut?
It felt like something inside Katsuki was changing.
As he was fucked into unrelentingly, Katsuki felt entirely exposed in a way he hadn’t—shouldn’t, a voice in his gut whispered—his entire rut.
His legs were spread, pinned to the bed leaving his legs wide open, his dick entirely ignored despite standing ramrod straight and leaking.
Izuku wasn’t accommodating or gentle—he was rough, almost aggressive enough to rival Katsuki in his heat himself in the way he squeezed Katsuki’s legs, pushed them to the bed, stretching Katsuki’s legs until he felt pushed to his limits.
His legs burned, he couldn’t breathe, Izuku was above him, around him, leaning down, panting in his face, sitting above him, pounding him. Izuku was everywhere, invading, penetrating, forcing himself into every part of Katsuki.
Katsuki could barely think—not when Izuku thrust inside so deep. He felt so full, every thrust reaching parts that made him gasp in sheer bliss, his hole fluttering helplessly, wanting to pull Izuku’s length back inside every moment he pulled out, but was completely helpless to Izuku’s pace.
He could feel his fangs coming out, throbbing wanting to bite, but he had nowhere to bite—Izuku was just out of reach with the way his legs pinned. He couldn’t help but drool, the slick spit leaking out of his mouth in a humiliatingly vulgar manner, fangs nearly vibrating with need.
Izuku was hitting so deep inside, Katsuki could feel his body buck and shiver with every thrust, muscles tensing and clenching with every move, hips rocking helplessly, wanting to whine and take him deeper, but being completely unable to do anything about it.
But something inside Katsuki kept screaming, ruining his pleasure, confused.
Why was he helpless to do anything but take it? He was a werewolf. He could just reach out, use his nails, dig into Izuku’s skin—not too hard, he wasn’t going to hurt his mate—but hard enough.
In fact, why wasn’t he doing just that? Why was he letting himself be treated like this—during his rut, especially? He was supposed to be—
Katsuki didn’t realize he was growling until Izuku leaned down and bit his lip.
Katsuki stared in shock, bottom lip throbbing. It wasn’t bleeding, but Izuku just bit him.
That was something he couldn’t take as anything but a challenge. Not just a challenge to Katsuki, but Katsuki's integrity as a werewolf.
Izuku only huffed a laugh, eyes narrowing in amusement, when Katsuki snarled, jerking his head forward to snap at Izuku, tell him exactly who was going to be biting who.
“Kacchan,” Izuku’s voice was so low Katsuki felt his dick throb in response to it. “You can’t be naughty. Not unless you want to be punished.”
Katsuki bared his teeth, ears raising in aggression at the implication. Why would he need to be punished? Even if he was studying under the legendary peacekeeper of the supernatural, Izuku was just Deku. Just a human. Katsuki wasn’t below him in any way. Not even during sex.
“I’m nobody’s bitch,” he snarled, baring his teeth at Izuku. “I’m not going to apologize for shit.”
“Oh?” A grin grew over Izuku’s face as his eyes sharpened, pushing his hips flush against Katsuki, lodging himself deep inside as he smirked at Katsuki in fond but smug amusement.
Katsuki shivered instinctively but then hated that he had that response. He had nothing to fear—especially not from his human boyfriend!
“Sorry Kacchan,” Izuku was excited, but it wasn’t the kind of excited that Katsuki rolled his eyes at, like when he was fanboying over a new werewolf trait he examined in Katsuki’s behaviour.
No, this was the kind of excitement that led to Izuku edging Katsuki for three hours straight or pulling out a new type of cock cage that he’d lock Katsuki into until Katsuki begged to cum.
It was a kind of excitement that equally aroused Katsuki as it warned him to be wary, making his tail stand to attention, tail wagging slightly. He narrowed his eyes at Izuku, trying to predict his unpredictable boyfriend’s next move.
Despite that, before Katsuki knew it, he was being flipped over, Izuku barely struggling to push flip Katsuki down face-first into the mattress.
Katsuki’s claws extended, but he didn’t get a chance to use them.
With his weight forcing Katsuki down, Izuku grabbed both of Katsuki’s wrists, twisting them behind to pushing them together in the center of Katsuki’s back. Using one hand to secure them together so that Katsuki’s claws couldn’t reach him, he used his other to force Katsuki’s face into the mattress, absolutely ramming him down, and bit down at the back of Katsuki's neck.
Katsuki’s eyes widened, and he growled, teeth bared as he bucked, thrashing. What the fuck did Izuku think he was doing?! He was forced on his hands and knees, ass up, face down, and now Katsuki had his neck bitten, face pressed into the pillow, during his rut, like some kind of—
“You’re my bitch now, Kacchan.”
Katsuki’s eyes glowed, and he growled, bucking, but before he could protest, Izuku thrust back in.
And damn if this position wasn’t perfectly suited to his prostate. Katsuki let out an angry, loud moan, arms struggling against Izuku’s grip, but Izuku was quick to tie him up. Katsuki growled, angry, but Izuku just thrust in.
“Kacchan is my bitch,” he repeated, voice panting and hot with his exertion as he pounded in and out of Katsuki’s hole. “Look at him, presenting so beautifully for me like this. He’s so pretty, looks like such a good boy for his mate, presenting so obediently.”
Katsuki’s body was rattled with every thrust, every jerk of Izuku’s hips dragging muffled growls and gasps and moans out of him.
He wanted to protest—he wasn’t presenting! He wasn’t being he wasn’t anyone’s bitch! He wasn’t obedient!
But he was just as conflicted. He was a good boy! He was the fucking best!
And Izuku felt so fucking good, pounding him silly like this, dragging cries and whines he never would allow out normally, his hands helplessly tied behind his back, he was helpless and obedient, but he wasn’t! He wasn’t being anyone’s bitch, but he was a good boy!
Izuku slowed down, hand tightening around Katsuki’s wrists, preventing Katsuki from moving, not letting Katsuki buck his hips back.
Katsuki completely even forgot his cock was lying between his legs, neglected. He wanted his hole stuffed and fucked until he fucking forgot his own name.
“Look at this,” Izuku’s voice was strained but smug. “You’re so subby and helpless underneath me. Who would ever think you’re a big bad werewolf when a dick in your ass gets you whining like a little kitten, Kacchan?”
Katsuki snarled, but Izuku held him down. He bucked and thrashed but all it did was make Izuku press against his prostate even harder.
Katsuki burned hot at the patronizing treatment, an annoyed hiss escaping him. He couldn’t just let Izuku-!
"You're such a whore for some good cock in your ass," Izuku noted casually, despite his strained voice. He pulled out, rubbing the tip against Katsuki's gaping pucker.
"W-who's the whore?" Katsuki sneered. "Fucking just put it inside again right this second you dumb fuck-"
Izuku squeezed his throat, making him completely lose his breath. He couldn't even protest when Izuku grabbed his jaw, keeping Katsuki's mouth shut.
"You think you’re going to get anything you want by mouthing off to me?” Izuku growled back, voice low and breath hot over Katsuki’s ear.
Katsuki bit his lip, only barely able to contain a whine of submission. He would not submit that easily.
“What a naughty wolf,” Izuku murmured, hand lowering from its tight grip on his jaw down to his neck again. “Are you going to ask properly this time or do you need me to give you a lesson?”
Katsuki panted, desperate as his hips bucked. “F-fuck you, shitty human,” he curled his lip defiantly.
"Kacchan was made for this, wasn't he," Izuku's voice was amused, pressing his weight down into Katsuki.
Katsuki tried to snarl, but his moans didn't help. "N-No I-"
"He takes me in so perfectly," Izuku continued, ignoring him. "His hole is so tight and perfect around me. Even during his rut, Kacchan can't help but need his ass fucked like the anal slut he is."
Katsuki's face burned. "F-fuck you!" he growled through a moan. "I am not a—"
"Yes you are," Izuku leaned down to nip at Katsuki's back, and fuck if that didn't make him hot. "Kacchan is a complete subby whore for a good dicking. See, just look at your hole," Izuku pulled out half-way, and Katsuki clenched down automatically, trying to keep it in, wanting it inside, deeper. "You're so desperate to be filled."
Katsuki growled, feeling his ears and neck heat with his blush. "I'm not—"
Izuku pulled out, slapping his dick against Katsuki’s hole. Katsuki felt his face burn with humiliation, the image of himself his mind conjured made him all the more aware of how pathetic he was behaving. Who ever heard of a wolf in rut being bound on their knees, ass up face down, eyes glazed over, tongue hanging out of his mouth, and drool dripping to the ground as he futilely tried to suppress his obscene moans and sobs for Izuku's dick?
Izuku pressed in just a bit, before pulling out, and repeating the motion.
It was entirely unsatisfying to only have the tip inside. Katsuki groaned in anger and need, hips pressing back, trying to take him in deeper, the proper dicking he needed.
"Just-just—" Katsuki sobbed.
For a moment, he felt himself freeze in horror and humiliation, realizing what was about to leave his mouth, but then Izuku's cock sank into Katsuki's ass, giving one long, hard thrust against his prostate.
Whatever reservations he had were immediately cast aside, his mind focused on the overwhelming pleasure crashing over him. But then Izuku pulled out, slapping Katsuki's ass with his cock a bit longer, moaning quietly behind Katsuki, evidently pleasing himself as he teased Katsuki. Katsuki's hole fluttered, and then Izuku pressed his head in, getting Katsuki's hopes up, but he quickly pulled out.
Katsuki couldn't take it any longer.
“Just put it in me, asshole!” he near screamed, teeth bared. He felt his body shake with a sob, and it made him stew in burning shame and arousal as he pressed his face forward into the sheets, trying to retain whatever dignity he had left by hiding his face.
Izuku wouldn’t let him have even that much. He ran a hand through Katsuki’s hair lovingly before yanking, pulling Katsuki’s hair back harsh enough to make Katsuki cry out as his head was forced back.
His ears twitched and trembled, the edge of pain as they were tugged only causing him to leak even more into the bed-sheets below him.
“Put it in your asshole?" Izuku repeated, infuriatingly teasing. "Kacchan really knows what he wants, huh? I'm surprised you're so open about being a cockslut. You want to roll over on your back, spread yourself eagle, spread your cute little ass cheeks and show off how hungry your gaping hole is, don't you?"
Katsuki hesitated, breath catching, ass clenching in arousal, wanting that. He could feel Izuku's smirk behind him. Izuku yanked at Katsuki's hair, using the motion to reveal more of Katsuki's pale, unblemished neck, sucking a hickey right over where his scent gland was supposed to be.
Katsuki squeezed his eyes shut, praying to every deity that he didn't cream himself right then and there.
Luckily, Izuku wasn't as in-tune with his werewolf biology as he normally was—or maybe he was and was just teasing Katsuki further, he wasn't sure—and pulled off his hyper-sensitive spot before Katsuki could humiliate himself any further.
"Well?" Izuku prompted. "Or perhaps Kacchan wants me to rail him so hard and fast he squirts, with his cute little ass in the air with no control as I fill his slutty little hole."
Katsuki couldn't help the long, slow moan that was elicited by the mere idea of Izuku doing that. His jaw fell slack, drool running down the side of his face as his lashes fluttered.
Izuku squeezed the arms going numb behind his back. "Come on, my pretty little wolf whore. What do you want me to do?"
This was fucking torture! It wasn’t fair! Why was he the only one that was going to look like a fucking idiot? Why didn't he care anymore?
Katsuki bit his lip, face burning with shame. He wanted to protest the name calling, but he wanted to be fucked more. He tilted his hips up quietly, suppressing his embarrassed sob in the pillow. Instead of curses and threats, his responding whimper made it clear what he wanted.
Izuku wasn't expecting this to go as well as it had. He had tried edging Katsuki earlier in his rut, and, well, Izuku was quick to learn that that was a mistake.
Katsuki did not take well to being denied his orgasm, and had gone nearly feral. Turned on Izuku, claws and teeth out in his heated fire, his passionate desire for release, and had turned them over. Izuku still had the bruises from that night.
Thinking about them only made him hotter, because the image of the violent, angry, aggressive werewolf fucking him until he lost his voice was now replaced with this version.
Katsuki on his hands and knees, hands held helplessly behind his back, tears streaming down his face, eyes glazed over in pleasure as he drooled. Izuku knew, at that moment, that he would do anything for Izuku's cock, and that he could finally get the response he needed to bitch Katsuki.
"Kacchan," he cooed, slowing his pace. Katsuki let out a small whine, unconsciously responding to the call. His eyes focused as the pleasure slowed, Izuku nearly pulling out.
The whines got louder.
"Come on Kacchan," Izuku soothed, rubbing a hand up and down Katsuki's slim side. "Tell me what you want."
"In," Katsuki pressed his hips back, rubbing his ass against Izuku's crotch, trying to find the dick and bury it back inside.
"You know how to say it like a good boy," Izuku prompted, lovingly giving Katsuki's ass cheek a squeeze. Katsuki whined, burying his face into the pillow and mumbling.
Izuku sighed. Still stubborn to the very end, wasn't he?
He pressed back in, cock started repeatedly ramming Katsuki right fucking there. The moment Katsuki relaxed, he stopped.
Katsuki whined. Izuku waited a moment, and then repeated the action. He fucked into Katsuki, giving him a moment of unrelenting pleasure, and then stopped.
It made him just as desperate as he was driving Katsuki, driven mad with the need to just continue and fuck him, dick him down good like they both wanted, but he had to make Katsuki say it. Katsuki had to beg.
And it didn't take him long to do just that.
" 'Zuku," Katsuki whimpered into the bed-sheets. "I want it."
Fuck that was hot, Izuku thought, mouth parting in awe. He was so tempted to give Katsuki what he wanted just for that alone, but he knew he couldn't give in. He repeated the teasing motion, stopping and starting as he knew would drive Katsuki wild.
"Dekuu," Katsuki's voice cracked when Izuku continued to hold back what he wanted. "In me-don't stop-"
"What do good boys say, Kacchan?" Izuku asked, voice gruff in his own strained arousal. "Say it, Kacchan."
"Just—" Katsuki sobbed. Katsuki could feel himself trembling at the question. How was he supposed to answer that without— he couldn't just beg for it! Wasn't it obvious enough that he wanted it, already? Izuku had him on his hands and knees, treating him like his personal fleshlight, fucking into him, hearing him wail like a baby over his cock. It was so unfair that he was torturing Katsuki like this.
Izuku continued to stuff him with his cock before stopping and driving Katsuki wild with need, over and over again until Katsuki was clinging to any sense of remaining sanity he had left.
"Come on, Kacchan," Izuku purred, pinching Katsuki's nipples.
Surely Izuku wasn't going to be that sadistic. Surely he wasn't going to make Katsuki humiliate himself any more than he already had? He wasn't going to be that cruel … surely?
"Say it, Kacchan," Izuku ordered.
His voice was so commanding, Katsuki trembled and his mouth obediently opened before he could control it, any reservations and shame cast aside.
His body knew better than to defy his Alpha.
“Just— please, Deku— ‘Zuku — p-please,” Katsuki sobbed. "Fuck me. Please."
Izuku had to stop moving to prevent himself from prematurely coming right then and there.
“Please,” Katsuki repeated, his voice a needy croak as he hiccuped, shameless with need. If he really had to degrade himself so horribly to get what he wanted, to feel good, to listen to Izuku and be his good boy, then so fucking be it.
“I need it, please ‘Zuku, just give it to me, I’ll be your good bitch, so j-just fuck me, please—“
Katsuki could barely speak, deriving into a loud, high noise of need as Izuku squeezed the base of his tail and thrust in as deep as he could.
“Good boy,” Izuku soothed, running his hand down Katsuki’s tail reassuringly. “You’ve been so good. So good for me, such an obedient, good boy. You’re the best wolf, Kacchan, the best werewolf, the cutest and most erotic one I've ever seen. My good boy.”
“I'm not cute,” he sneered, voice weak. “But of course I’m the fucking best.”
“Of course you are,” Izuku soothed, rubbing the base of Katsuki's tail, loving how it made Katsuki twitch underneath him. “You’re so good, you beg for me so well, Kacchan. It's so cute.” Izuku watched how Katsuki’s ears twitched at the word beg.
But he didn’t deny it.
Izuku grinned. “You deserve a treat.”
Izuku bit back a laugh when he saw the way Katsuki’s back arched at the word treat. He squeezed Katsuki’s tail, as he pulled out, making Katsuki whine quietly but otherwise not protest at Izuku’s retreat, despite his desperation to just get the hard dicking he needed.
Izuku leaned back to take in the view.
Katsuki had his arms crossed behind his back, keeping himself in that position despite Izuku not saying anything, instinctively knowing to be good. His back was arched almost impossibly high, his lean muscles strained and covered in a sheen of sweat.
Legs spread beneath him to brace himself, he was full-on presenting, shaking his ass from side to side enticingly, impatiently, yet still obedient at the promise of reward. Izuku couldn't wait to give him everything he deserved.
A good dicking was definitely a part of what Izuku had planned, but it wasn’t the whole surprise.
It took barely a moment for Izuku to set up the fake knot around the base of his cock. He’d already tried it out earlier, fucking into one of Katsuki’s used fleshlights, but it was absolutely incredible how well and comfortable it was around his dick. Rather than suffocating or compressing it as he feared, it fit like a warm, wet glove around the base of his cock. It would inflate right around when Izuku ejaculated, able to sense differences in sperm count to an incredibly precise degree, and then triple Izuku's cum at the very least.
Modern technology was amazing, Izuku thought, wrapping his hand around the large piece. He'd been doubtful when Dr Torino brought it up, thinking it would be similar to a knotted dildo, but this was so much better.
With the help of this artificial knot simulator, Izuku could complete the bitching with the most important step: knotting Katsuki and breeding him full of his cum until his stomach bulged with how full he was.
Katsuki was leaking in need on the bed, still presenting with his ass up, face down, and head tilted to display his neck. Izuku took a moment to appreciate the sight of Katsuki's tail wagging in anticipation, his dick weeping a thin stream of pre-cum to create a small pool on the bed below him, as he held his hands behind his back.
So cute, Izuku thought. Katsuki was so needy, but he still waited so sweetly. Izuku wanted to lean down and lick the little pool Katsuki's cock had drooled on the bedsheets, but he was interrupted by Katsuki's whiny growling.
“What the fuck are you waiting for?! Did you already come, you shitty nerd!” Katsuki snarled, distraught desire in his voice. “Are you going to fuck me or not?” he near pleaded.
Izuku wanted to play with Katsuki—it was so incredibly cute to see him splayed in the position he was in, especially knowing what it meant to wolves. Katsuki was completely exposing every part of himself, submitting not only his body but also his soul, his werewolf pride completely discarded to submit beneath Izuku.
He would have his fun later, Izuku promised himself. After being there for his boyfriend for almost 3 weeks, he thought a bit of play-time was well deserved. But he would help his poor, needy boyfriend first, he decided, tugging at the base of Katsuki's tail.
Katsuki’s hips tilted higher, his hole fluttering, displaying the most delicious gape Izuku had ever seen.
The sight of Katsuki’s stretched hole clenching over nothing like that, desperately seeking to be filled, was too much for him to resist, and he thrust back in, sinking his hands into Katsuki’s side, pulling them flush against each other.
Katsuki let out a long, relieved moan when Izuku finally pressed his hips flush against Katsuki's behind, almost fully sheathed inside Katsuki. He was so relieved to be filled that he didn’t even notice the strange sensation at his entrance.
Izuku was hitting him just right, every thrust causing Katsuki to see stars. His tail and cock jerked helplessly with every slap of skin against skin, leaving him aching but pleased.
Katsuki could feel his dick rub against the bed with Izuku's every move, his repeated smacks causing Katsuki's entire body to helplessly jerk with him. It swung between his legs, hard, heavy, leaking, aching, but instead of trying to touch it, he settled for gasping into the pillow.
Izuku's cock slammed into his prostrate repeatedly as his thrusts quickened, leaving Katsuki helpless to the stimulation, his own cock leaking between his legs.
Fuck, he realized absently.
This was the first time he'd had his prostate milked by Izuku's dick like that during sex. His swollen, aching erection, didn't even need to be touched—he realized with awe he might be able to come from penetration alone for the first time during his hea—rut.
Katsuki's brow twitched slightly when he realized there was something weird. Izuku wasn't wearing a cock ring, and Katsuki was pretty sure he was naked. But when he tried to turn behind to see what was going on, Izuku grabbed Katsuki's arms, pulling them back tight, and grabbed Katsuki by the front of his neck, arching him off the bed.
Katsuki gasped, but the hand around his throat tightened, leaving him barely able to breathe, nevermind see what Izuku was doing.
"W-wait-" Katsuki gasped. The odd bumping against the rim of his hole only continued, the pressure increasing, stretching him bit by bit, and he thrashed underneath Izuku. "Deku-'Zuku, wait, wh—"
Katsuki broke off into a startled moan when Izuku forced his head to the side, displaying his neck fully, near forcing Katsuki to submit. His arms were still held behind his back, almost numb from being held down, but he tried to pull them away futilely, protesting.
Izuku nipped his scent gland, and Katsuki froze.
Fuck. He could feel his Alpha's knot catching against his rim. An anguished, choked keen escaped him when he felt it slip in half-way, so close to being fully inside, before it slipped back out, only to be forced back inside over and over and over.
Izuku was fucking him like he normally would, in and out, and the knot stretched his hole repeatedly, slipping in and out. It was so delicious being stretched so impossibly wide, Katsuki could feel the drool and tears streaming down his face as his eyes rolled back into his head in pleasure, but he was nearly inconsolably desperate within a few moments, wanting his Alpha's knot just in him.
He didn't have to wait long to get what he wanted.
The moment Izuku's knot popped and locked in, Katsuki was gone. Just like that, he was falling. Crashing. Sobbing, whining, trembling and shaking uncontrollably as his body shook with waves after waves of pulsing pleasure, from his head to his leaking, spurting cock, to his ass, clenching impossibly tight around the massive knot pressed right up against his prostate.
Every hot spurt of his Alpha's cum drenched his insides, leaving Katsuki helpless to do moan with reckless, broken abandon, his eyes fluttering shut in contentment. The wetness from his own cock spurting on the bed as he came was barely recognizable compared to the pleasure of getting his ass stuffed full.
He didn't bother to tamp down his delight—didn't think he could, really. His purring and keening and whimpering echoed in the room around him as his ass clenched, trying to suck out every drop out of his Alpha's knot, wanting it to fill him until his ass was leaking with it, shooting wave after wave of warm cum inside, deep inside, feeling it until he was forever imprinted with the sensation of the most pleasurable thing life had to offer.
Katsuki could feel the way his stomach bulged with his Alpha's seed.
It was so hot, so thick, so large, he was absolutely frozen, all muscles tightened and clenched in his climax. He didn't even hear what Izuku was saying behind him past that he was a good boy, so good, taking it so well, so good. The only thing on his mind was the soothing relief pulsating throughout his entire being as he was filled with his Alpha's hot seed.
Katsuki could feel and see the bulge from the sperm and knot and Izuku’s dick in his stomach. He had never been so thoroughly fucked in his life. This was contentment and pleasure unlike any other he could even fathom.
Fuck. Why would he ever want to be in a rut when he could be bred?
Like a light switch, something inside Katsuki shut down, and he lost all energy. Katsuki collapsed to the bed, muscles instantly relaxing, knowing Izuku would hold him up. Nothing mattered—nothing except being filled by Izuku. And he was filled, so he was happy, content, satisfied for once. The endless frustration and ache of the rut was gone, and when Izuku reached under Katsuki to press against where Katsuki's stomach bulged with cum, Katsuki whimpered, going slack into his arms.
The burning fire had been put out. All that was left was comfortable, smoking embers, just hot enough to keep Katsuki's insides warm. Izuku's dick was the water that put his fire out.
Katsuki had never been more content in his life, body arching back into Izuku's, seeking more of the reviving elixir that was Izuku's dick, so damn happy to be free of the ache of his rut. He didn't even realize he was purring.
Oh, Katsuki realized sleepily, lazily rubbing a hand over the bulge of Izuku's sperm and cum in his belly, completely satiated. I guess the bitching worked after all.
“No! Of course you can’t fucking pull out!” Katsuki snapped.
Izuku froze. “What?” He asked, a hint of a whine in his voice. “It’s been twenty-five minutes, Kacchan, surely that’s enough—”
“Like hell it is!” Katsuki scowled. “Don’t you know anything?!” Katsuki shot a glare over his shoulder.
Izuku sighed helplessly, wincing when Katsuki’s aggressive roll back over caused his oversensitive dick to twitch in Katsuki’s ass.
“You’re the most useless fucker on the planet!”
“What am I supposed to know?” Izuku asked, tired but exasperated fondness in his voice. Katsuki ducked his head forward, wolf ears folding over, sulking, and Izuku lightly rolled his eyes but pressed a kiss to his boyfriend’s shoulder.
“Shitty Deku,” Katsuki grumbled, probably pouting. Izuku could hear it in his voice even if his face was turned away. “If you’re going to bitch me, you’ve got to do it properly, you dumb human.”
Izuku cocked his head, frowning. He’d done everything Dr Torino and the fanfictions had outlined. What was left for him to do?
He’d made sure to get Katsuki to submit to him, to present himself willingly and beg for dick. He’d knotted Katsuki, and despite how overstimulated he felt, he let Katsuki cockwarm to finish the breeding. What left was there to do?
Izuku glanced curiously at the back of Katsuki’s head, and Katsuki curled in on himself further, his head ducking in. Izuku glanced at the smooth skin of his neck and quietly gasped. Katsuki’s ears twitched towards his voice, but he refused to respond.
“Sorry, Kacchan,” he apologized, shuffling closer to press a kiss to the back of Katsuki’s neck. “I didn’t collar you.”
Katsuki was silent for a long moment, though his tail twitched in excitement.
“That’s not it, dumbass,” Katsuki’s voice quietened. “ ‘S not wrong, but it’s not right either.”
Izuku couldn’t decipher that. “What?”
Katsuki let out a small rumble of annoyance, but the choked manner in which it came out made Izuku realize he was embarrassed.
“Collars are whatever,” Katsuki huffed, trying to sound flippant, but Izuku caught the desire in his tone and grinned. Katsuki wanted to be his good little pet all around, huh? “You—”
“‘You?’” Izuku echoed when he refused to complete that.
“You. You’re an incompetent piece of shit!” Katsuki exploded, face and ears blooming red. “You didn’t mark me, you shitty human!”
Izuku blinked blankly. Marking… that was the biting thing, wasn’t it? Katsuki liked biting Izuku, leaving scars on the back of his neck that eventually just healed over until Katsuki got pissed at how his marks were fading and re-did them. Katsuki wanted Izuku to do that to him too?
“How am I supposed to bite you hard enough to break your skin and scar you with my teeth?” Izuku asked, a bit horrified by the concept. “Humans generally frown upon cannibalism.”
Katsuki let out an annoyed sound. “You don’t eat me!”
“I already did,” Izuku teased, pressing a kiss to Katsuki’s shoulder. “Well, I technically ate Kacchan’s ass, but Kacchan is an ass, so I guess that—”
Katsuki felt no remorse for violently elbowing Izuku in the guts. Izuku, wincing, laughed, grabbing Katsuki’s offending arm and lacing their fingers together as Katsuki tried to elbow him again.
“I’m fucking leaving the moment your shitty fake knot goes down,” Katsuki hissed. Izuku couldn’t help his cheeky laugh.
“Kacchan, you’re not going anywhere,” he refuted, snickering at how the happy swish of Katsuki’s tail against Izuku’s stomach betrayed his grumpy countenance.
Izuku wasn’t surprised that despite his grumbling, Katsuki didn’t deny his claim.
Wolves mate for life, after all, he thought, pressing a sweet kiss to Katsuki’s neck before biting in.