Chapter Text
Izuku felt weird.
If he was honest with himself, he could admit that he’d been feeling weird for at least the past three days. A general malaise had taken over his body, and he couldn’t pinpoint the exact source. He only knew that his appetite had been off and his clothes felt too scratchy on his skin, like he’d dunked them in a bucket of sand before putting them on. And while it made sense to feel hot at the tail end of August, his school uniform had never made him sweat quite this much before.
The air was stagnant as he walked past the main building gates of UA, so he tugged on his collar a few times to create an artificial breeze down his neck. The relief he experienced with the action was minimal.
Finally back from his two month work-study at Lemillion’s agency, he was excited to see everyone in class again. Since he and the rest of Class A lived together in one of the third year dorms, he’d been able to see his friends in passing quite often. But as their longest and most demanding work-study yet, it’d been difficult to do much together apart from sharing quick meals in the common area, and that had only happened on the rare occasion that their schedules aligned. Needless to say, Izuku was eager to find out what everyone had been up to under the tutelage of their respective pro heroes.
“Deku, wait up!”
Izuku paused and looked over his shoulder. A short distance behind, he found Ochako running to catch up to him with a big smile on her face.
“Hey, Ochako,” he greeted with a smile of his own, and started walking as soon as she caught up.
“Hey! I feel like I haven’t really seen you around,” she said, slightly out of breath. After a quick scan of his face, her smile fell. “Oh my god, are you okay? You don’t look so good.”
“I’m fine,” he assured her, and when her eyes narrowed suspiciously, he added, “I might’ve gone overboard with the hours this week.”
“Ah.” Her eyes softened sympathetically. “Well, I’m sure Lemillion kept you busy. He’s in the Top 10 for a reason!”
Izuku nodded as they entered the building. Though Ochako was right in that Mirio-senpai had given him very little time to rest, it had also been fun to work with him again. Izuku couldn’t remember the last time he’d laughed until he cried, but that had been a regular occurrence while working alongside the Number Six hero. Despite the many tough calls they’d responded to over those two months, their severity paled in comparison to the horrors he and Lemillion had witnessed while dealing with the Shie Hassaikai during his work-study under Sir Nighteye, so Izuku would rate the experience as a positive one overall.
Once they made it to class, Izuku and Ochako were greeted by their friends like they hadn’t all been living under the same roof, which warmed his heart. There was little more comforting to him after an extended period of handling daily crises than having casual, easy conversations with his friends.
“Midoriya!” Sero said, wrapping an arm around Izuku’s shoulders and gesturing at Mineta with his thumb. “Can you tell this fool how time consuming it is to make gyoza from scratch? He says he wants to make them tonight but we’re gonna have a crap-ton of homework by the end of the day!”
While the school provided them with three meals a day in the dining hall, they also had the option of cooking in their shared dorm kitchen, which Izuku had started doing a little more of this year, mostly as an excuse to spend additional time with Kacchan, who used the kitchen more than anybody else. Something about the school counselor suggesting he take his anger out on the vegetables. And maybe it had worked to some extent, since Kacchan had mellowed out quite a bit over the past two years, though he did blow a fuse every time Izuku messed up his instructions, which was almost every time they cooked together. To be fair, they were both getting better; Izuku at communicating when he didn’t understand a step and Kacchan at explaining again without insulting Izuku’s entire lineage.
In response to Sero’s plea, he was about to say that making gyoza from scratch would take about an hour and a half, not including the ingredient shopping, when a sudden memory of his mom neatly pinching stuffed gyoza wrappers popped into his head out of nowhere and his heart grew heavy.
“Yeah, it…takes a while,” he finally managed, eyes gathering moisture, and both Sero and Mineta gaped at him.
“Woah, you good, bro?” Sero asked, patting him on the shoulder. Izuku hurriedly wiped the tears away before they could spill.
“Yeah, sorry,” he said with a soft laugh. He didn’t know what was wrong with him. That was the third time this week that he’d had an overly emotional response to something innocuous.
The first had been two days ago, when he’d gotten teary eyed at the sight of an old man feeding a stray cat, and the second had been last night, when he’d burst into tears over a deep wrinkle in his uniform shirt that he couldn’t seem to iron out right.
From the next group over, Iida approached, gaze sympathetic. He lifted his hand, as if to pat Izuku’s shoulder, but to Izuku’s surprise, the class rep’s expression turned to something like shock, and his hand froze in midair. Then he blinked quickly before letting his hand drop to his side.
Izuku tilted his head inquisitively, but Iida avoided his gaze, cleared his throat and took a step back.
“It’s good to see you, Midoriya,” he said stiffly before heading to his seat.
As strange as the interaction was, Izuku didn’t have much time to dwell on it before his attention was again caught by Sero’s food conversation.
He forgot about it until a few minutes later, when Shoto entered the room and greeted everyone with a small smile. But when he shuffled past Izuku to reach his desk, Shoto’s entire body tensed.
“How was your work-study, Todoroki?” Ochako asked, oblivious to the abrupt change in the alpha’s body language.
Shoto stared at Izuku with a puzzled expression for a moment before his gaze darted back toward Ochako.
“It was fine,” he muttered, but his voice sounded strained, almost like he hadn’t gotten a full breath before speaking, and he stumbled over someone’s backpack in his rush to reach his seat at the back of the class.
Startled, Izuku stared at his retreating form. Beside him, Ochako was doing the same. She leaned in close to him and whispered, “That was weird, right?”
“Yeah,” he agreed, concern causing his chest to tighten.
He couldn’t help but worry that Iida’s and Shoto’s changes in demeanor were because of him. Normally, they would’ve stayed to chat for a few minutes with everyone else. But after approaching him for only a moment, they’d hurried to their seats, and now they avoided his gaze like they owed him money.
Had he unknowingly done something to offend them? A twinge of hurt embedded itself in his heart and he blinked back the fresh threat of tears before it could become apparent.
He made a mental note to ask them about it later.
After exchanging short work-study tales with his other friends, the bell rang and everyone migrated to their seats. Despite how much Izuku enjoyed catching up with everyone, he was quietly grateful for the opportunity to sit down. His body felt heavier than it had when he’d first arrived, and though he’d unbuttoned his blazer earlier, he could still feel beads of sweat rolling down his back. He really hoped he wasn’t catching a summer cold.
Their seating positions hadn’t changed since first year, and Izuku was happy to still sit behind Kacchan. Their complicated relationship had steadily grown into something resembling the friendship he’d always dreamed of having with his rival, and though Kacchan still had a short temper, Izuku could sense that his occasional outburst was no longer tinged with resentment toward him.
“Hey, Kacchan,” he greeted as the blond settled into his seat. “What was working with Mirko like?”
Over the past two months, he’d spent a significant amount of time wondering about that, especially considering that Mirko, the current Number Two hero, had a personality that was just as intense as Kacchan’s. He could only imagine the constant bickering that had occurred between them the entire time. And he’d asked, but Kacchan, who was notoriously bad at replying to texts, had given him short, vague answers and only responded to messages right before his 9pm bedtime. Kacchan didn’t spend much time in the common area of the dorms, either, so they hadn’t had time to have a proper conversation there.
Kacchan side-eyed him as was customary, but his double take was definitely not. He scrutinized Izuku’s appearance with a frown. “The hell happened to you?”
Izuku let out a small laugh to hide the sting in his heart. “Do I really look that bad?”
“Like shit,” Kacchan confirmed, then paused, brow twitching as he leaned into Izuku’s desk and sniffed the air. Izuku self-consciously leaned back. He’d showered last night instead of this morning, and had been sweating for a while now. Did he stink?
His cheeks burned as red eyes bore into him, searching. Then Kacchan froze for a moment. His gaze darted briefly around the room before focusing on Izuku again. His lips parted, and Izuku braced himself for a harsh remark. But before any words could make it out, Present Mic burst into the room with a loud, “Welcome back, everyone! Can you believe I actually missed you brats?”
Izuku turned his attention to him, surprised to see him instead of their homeroom teacher. As if reading his mind, Mic added, “Aizawa’s gonna be out for a few hours, but he’ll be back in the afternoon. Don’t think I’m gonna take it easy on you, though!”
From the corner of his eye, Izuku saw Kacchan let out a huff before turning to face the front.
He did his best to concentrate on the lecture, but it was hard to keep up with Mic’s interminable tangents when a pain started to bloom from his lower belly. At first, he thought nothing of it. Maybe he’d eaten something last night that wasn’t sitting right with his gut. Except he hadn’t eaten anything outside of his usual diet.
Because of the many ways he’d broken his body over the past two and a half years, his pain tolerance was sky-high. He could handle broken bones like a walk in the park, but this pain was different. It was deep and searing, like someone had decided to stick him with a fire poker and wiggle it around.
Kacchan shot him a glance over his shoulder, but the last thing Izuku wanted was to distract him or anyone else, so he kept his eyes glued to their teacher.
Soon, he could feel sweat pouring from his face, and every breath he took was painful. There was a strange buzz coming from somewhere around him, though it also felt like it was vibrating directly in his ears.
He couldn’t think, couldn’t breathe, and his vision was growing hazy.
Then a blurry Kacchan split into two as he fully turned around in his seat, the scowl on his face more confused than aggressive. His voice was distorted, though uncharacteristically soft.
“The fuck, nerd?”
Izuku opened his parched mouth to respond, but Kacchan’s name got stuck in his throat. Then his vision went dark.
*
From the moment Katsuki had laid eyes on Izuku, he’d known something was wrong. The nerd looked like he hadn’t slept in days, the dark circles under his eyes a stark contrast against the rest of his face. And he was sweating, which was weird because Katsuki wasn’t, and due to the nature of his quirk, Katsuki was usually the first to break into a sweat out of anyone else in class.
Then he’d caught a whiff of something new emanating from him.
As an alpha, Katsuki’s nose was sensitive. Though Izuku’s beta scent was mild, Katsuki would know its gentle, citrusy notes in the middle of a crowd during rush hour. But today, it had shifted into something intensely sour, and when Katsuki recognized the uncontrolled wave of pheromones mixed into it, his blood ran cold.
Mating pheromones? From a beta?
His pulse spiked and his mouth watered like he was getting ready to eat grilled meat.
What the fuck?
He’d been hit in the face with an omega’s mating pheromones too many times to count–he was, unfortunately, quite popular with the underclassmen extras despite his best efforts to repel them–but in all of those instances, he’d never experienced a reaction that wasn’t overwhelming disgust.
What the fuck?!
He had every intention of demanding answers from the nerd, but the confusion in his big green eyes gave him pause.
Was it possible that he didn’t know what was happening, either?
A quick scan around the room confirmed that most of the class hadn’t noticed anything amiss, which wasn’t surprising, given that it consisted mostly of betas. Denki was the only omega, but his entire body was turned away while he talked to Sero, and he seemed oblivious to the situation.
There were, however, three other alphas aside from himself–Iida, Yaoyorozu and Todoroki–and when he met their gazes from across the room, he realized that they were all keenly aware of Izuku’s predicament, too.
Both the class rep and Todoroki were not-so-subtly covering the lower half of their faces with their hands, while the usually placid Yaoyorozu twirled her hair over and over, brow furrowed as her leg bounced under her desk.
Katsuki’s gaze flicked back to Izuku, but before he could speak, their loud-ass cockatoo of a teacher entered the room with a rowdy greeting. Izuku turned his gaze to the front of the room, and Katsuki reluctantly did the same. But he couldn’t stop thinking about it.
Could it be that Izuku was presenting as an omega?
Most people presented between the ages of 13 and 16, so he supposed 18 wouldn’t be that wild of an anomaly. But weren’t omegas supposed to smell sweet?
He shot a glance over his shoulder.
How the hell could the moron not know something was off? Was he so used to disregarding his body’s signals that he couldn’t recognize when something was wrong anymore?
When Izuku ignored his inquiring gaze, he forced himself to look forward and take notes as Mic spoke, even as he rambled on about topics unrelated to the lecture. Anything to distract from the fact that he had to limit his breathing. Because every breath he took of Izuku’s heady scent made his skin rise with goosebumps.
He ignored it until he absolutely couldn’t anymore.
Izuku began to make a high-pitched, vibrating noise that sounded a lot like a distressed purr, and when Katsuki turned around to face him, he found that his countenance held a greenish hue.
A spark of fear ignited in his chest. “The fuck, nerd?”
Izuku’s eyes were blank when they slowly moved to meet Katsuki’s gaze, breaths shallow as he mindlessly pulled on his shirt collar. When his lips parted, he only managed a soft “Kacch-” before his eyes rolled back and his head dropped forward.
Katsuki’s reflexes were fast enough to catch his forehead before it hit the wooden desk, and he jumped to his feet to keep him from sliding out of his chair.
“Oi, dumbass!”
He scowled as his palm grew hot against the nerd’s skin. Their classmates quickly stood from their desks and surrounded them.
“Midoriya!”
“Oh my gosh! Is he okay?”
Present Mic hurried over, too. “Yo! What’s going on?”
Katsuki pushed Izuku’s drenched hair away from his forehead. “Idiot’s burning up.”
Izuku let out a shuddering breath and blinked slowly. His half-lidded gaze remained unseeing, and when Katsuki worked his blazer off, the white shirt underneath was soaked. Their classmates let out varying sounds of shock.
“Holy crap, Midoriya!” shouted Denki when he caught sight of the fabric sticking to Izuku’s back. “Can you hear us?”
Izuku did not respond.
Recalling the way he’d tugged on his collar before he passed out, Katsuki loosened the nerd’s tie and undid the first two buttons.
“Bakugo, would you mind-” Present Mic began, but Katsuki had already hoisted Izuku into his arms before he could finish asking.
“On it.”
“Hey man, do you need any help?” Eijirou asked, glancing with concern at the compression sleeve on Katsuki’s injured arm. Though it’d been over a year since the battle that permanently fucked his arm up and he was far from having full function of it, he’d gained enough strength back to be confident that he could carry something much heavier than Izuku for a few minutes, at least.
“Shut up,” he snapped, tilting Izuku into himself so that his head rested on his shoulder. “I said I’m on it.”
“You sure?” his friend asked again, reaching out.
The implication that he couldn’t complete such a simple task when he’d been out on patrol with the Number Two hero around one of Tokyo’s most dangerous sectors for two months raised Katsuki’s hackles, but he’d improved at keeping his outbursts over perceived offenses to a minimum, which was why he startled himself with his own reaction. Before he could understand what was happening, he bared his fangs at Eijirou with a growl, and instinctively pulled Izuku away from his grasp.
The class immediately fell silent.
“Woah, easy now,” Mic said, and Katsuki blinked, just as shocked as the rest of his classmates. When Eijirou raised his hands in a placating manner and stepped away, Katsuki’s cheeks stung with shame. What the hell had gotten into him?
Averting his gaze from his friend’s hurt expression, he tightened his hold on Izuku. The small crowd around them parted and he hurried out of the room without another word.
The infirmary was located at the opposite end of the building, two floors down, and as he made his way there, he replayed what had just happened. It didn’t make any sense for him to snap at Eijirou like that. He trusted the guy with his life.
He’d been his first friend at UA, the toughest and simultaneously kindest guy he knew, apart from Izuku. He’d been the one to teach him about friendship and helped dull some of his sharpest edges so he could become a better version of himself.
He knew for a fact that Eijirou hadn’t meant to undermine him in any way, and he’d never do anything to hurt Izuku. So why had his body reacted like that?
He couldn’t help but be disturbed by the sudden loss of control.
After all, with his weak arm, it would’ve made sense to recruit his classmates’ assistance in carrying Izuku. At the very least, it would’ve been helpful to have Uraraka temporarily eliminate his gravity.
Izuku wasn’t small. He was almost as tall as Katsuki, and built thick with muscle from years of combat training. So why had his alpha senses overreacted to the point of making a nonsensical decision?
He snuck a glance down at the nerd. Right now, with his body limp and feverish, he looked more vulnerable than Katsuki had seen him in a long time. It was unnerving.
A soft whimper shook him out of his rumination. Izuku stirred, mumbling something unintelligible. Then he clutched at his stomach and his breathing became shallow again.
Katsuki was grateful that the halls were relatively empty. Occasionally, a student or faculty member would stare and recognition would flood their features, because yeah, who the fuck didn’t know the boy who saved the world by now, but they looked away quickly enough when Katsuki shot them a murderous glare of his own. Izuku was probably going to shrivel up with shame when he found out he’d fainted in class. He didn’t need a bigger audience to see him like this.
Once in front of the elevators, Katsuki kicked the call button and growled when the doors didn’t immediately open. Izuku’s panting was getting louder and Katsuki was going to go insane, listening to it. Pulse pounding in his head, he shouted with relief when the damn elevator finally opened. He rushed in, punched the ‘1’ button then spent a good ten seconds slamming the stupid ‘door close’ until the doors actually closed.
But of course, Katsuki’s ordeal could only get worse.
Izuku began to nuzzle into his neck, and his warm, heaving breaths made Katsuki’s skin tingle from head to toe.
“The hell are you doing, freak?” he hissed, but Izuku didn’t seem to hear him. He went so far as to grasp Katsuki by the throat to hold him in place and tug the edge of his collar down. Katsuki recoiled at the unexpectedly strong grip, at the sudden breeze on his exposed neck. Then there was wet heat directly over his scent gland and he jolted with a curse, nearly dropping the nerd. Sparks ran all the way to his groin, along with a familiar pooling of heat.
Izuku hummed and licked him again.
“Gah! The fuck is wrong with you!” Katsuki bellowed, rocking the elevator car as he knocked into the wall in his attempts to pull away. He seriously considered dropping the pervert and leaving him there to be found and shamed by whatever random extra happened to show up.
But then he noticed that Izuku’s constant stream of distressed pheromones had been cut off completely. He growled, annoyed by the flood of conflicting emotions that ran through him at the realization.
He hated this. He really fucking hated it. Hated being touched, having his personal space invaded. If anyone else tried to get this close to his neck, he’d absolutely have their heads.
But…this was Izuku. And Izuku was always an exception. As much as it irked him to admit it, Katsuki had yet to find one thing he wouldn’t do for him. It wasn’t even that he was still trying to atone for the years worth of shit he’d put him through. It just…almost came naturally these days, to want him to be okay.
Ugh.
And while he wasn’t sure what his own pheromones were communicating in his flustered state, the moron was obviously taking some kind of comfort from them. He didn’t want to think about how close he was to pitching a tent. It was the first time he became aroused in public in years , and he wanted to throttle the nerd for making him revert to his early puberty days. But he also couldn’t, in good conscience, bring himself to take his one source of comfort away when he was delirious with pain.
So instead of drop kicking him like he really, really wanted to, he squeezed his eyes shut and dug his fingers into him. Because why the fuck did his tongue have to feel like that?
And why did the sound of his contented purr have Katsuki’s alpha absolutely beaming with satisfaction?
He cursed Izuku and his ancestors and his future offspring while the bastard lapped at his neck, chest vibrating, low and steady.
Then the elevator pinged and the doors opened right in front of the infirmary and Katsuki bolted.
All the beds were empty when he burst inside, and he dumped the nerd into the first one he saw. Izuku immediately curled in on himself with a miserable whine. The sour flood of distressed pheromones began with renewed intensity, but Katsuki couldn’t take it anymore. His skin was on fire and the situation in his pants was not getting any better.
“What’s going on?” asked a nurse he did not recognize. They were short and stout and had a lizard head. They flicked their forked tongue, which Katsuki vaguely remembered was something reptiles did to pick up scent particles, and let out a soft, “Oh my.”
“Yeah,” Katsuki huffed, glaring down at Izuku. Only then did he notice that the nerd’s pants were soaked through, but not with sweat.
He stared, pupils dilating when an altered version of Izuku’s lemony scent hit him. There was a hint of sweetness to it now that reminded him of the magnolia trees they used to climb together as kids.
This time, when Izuku let out an agonized moan, it had a profoundly different effect on him. His heart went haywire and his ears began to ring the way they did whenever he set explosions off in an enclosed space. Before he had a chance to think, his body moved on its own.
He leaned over Izuku’s writhing form, neck exposed to grant him comfort. Izuku clutched at the front of Katsuki’s uniform and nuzzled into him again.
”Alpha,” he whimpered.
Then there was that sweet, wet heat against his neck again, and Katsuki failed to stifle a groan. The waves of distress subsided and a warm serenity washed over him in a way he’d never felt before. Absentmindedly, he carded a hand through Izuku’s hair, closed his eyes, and breathed him in.
He smelled so good. Familiar, even though he’d never emitted this particular scent before. And his hands felt so good against Katsuki’s skin. He never wanted to be away from him again. A low rumble formed in his chest- a sound he’d never even known he could make. But it felt right. It felt perfect.
In his peaceful trance, he vaguely registered a third presence around them, but its voice was muffled and unimportant. At least, until the presence touched his shoulder and he snapped his head around to snarl at it.
“Young man?” the presence– the nurse –asked, tone wary. “No need for hostility. I only asked if you were his mate.”
Katsuki blinked quickly and the trance broke. “Hah?!”
He yanked away from Izuku so violently that he fell on his ass.
The nurse tilted their head curiously, and Katsuki realized with dismay that he was hard.
Before the lizard nurse could speak again, Katsuki jumped to his feet and stormed out of the infirmary, leaving Izuku’s intoxicating scent and cries of pain behind.
He rushed past nameless extras who quickly moved out of his way, burst through the front doors, and just kept running. He ran until he reached the dorms and when that didn’t seem far enough, he kept going.
He ran past the front gates and away from campus, uncaring that his heart felt ready to explode. He didn’t stop until the ringing in his ears was overtaken by the obnoxious drone of cicadas and he somehow found himself standing in front of a coffee shop he knew his friends loved going to, quite a distance from campus, gasping for air. Thankfully, his arousal had died down with the exertion.
He wove a shaky hand through his hair and focused on settling his breath.
What the fuck.
What the fuck!
He’d always thought of secondary gender bullshit as stuff that could be easily managed because that had always been the case for him. He’d never experienced something as demeaning as losing his mind to…whatever the fuck that had been. In his eyes, anyone who abandoned sense in favor of their animalistic urges was a pathetic fucking loser. And yet…
He dragged his hands over his face and groaned, unable to even think about it without his cheeks burning. He’d gotten worked up enough to pop a boner in public.
All because of Izuku’s scent…and his…his slick…
Fuck. This was so beneath him!
But he’d be damned if he said that wasn’t the single most delicious thing he’d ever smelled.
*
Izuku slowly blinked his eyes open.
He’d been in this room plenty of times over the past two years to recognize it as the school infirmary. He couldn’t remember getting injured, though. In fact, his memories after finding out Present Mic would be covering for Aizawa-sensei were fuzzy, at best.
He could remember being hot and in a lot of pain. People calling out his name. And floating in the air for a while. But that was about it.
His head felt as if it were stuffed with cotton and he was sore all over, like he’d gone back in time to the first months of brutal training All Might had subjected him to.
Slowly, he sat up and swallowed with difficulty. His throat was so dry.
He looked around and found a water bottle on the bedside table. He grabbed it and drank the whole thing in one go. Relieved, he licked over his chapped lips and frowned.
Hold on.
He ran his tongue over his teeth and along the roof of his mouth.
That was…odd.
His mouth was coated in an oily film that held a strange flavor. It was smoky and rich, like burning firewood with a hint of spice, but the most disconcerting part about it was that it made him feel a certain way.
Every time his taste buds sensed it, an undeniable tranquility enveloped him, like being nestled in a warm embrace. But how on earth did that make sense?
He moved his tongue around some more, trying to remember what he’d had for breakfast, to figure out where such a flavor could’ve come from, but the more he tried, the fainter the taste grew.
His chest ached a little at the realization that it would disappear entirely before he had a chance to figure out what it was.
The sound of a cane and approaching footsteps drew his attention. He knew that sound very well, too. Soon enough, the curtain around him was pulled back and Recovery Girl’s tiny form appeared at the foot of his bed.
“Well, well. If it isn’t Mr. Midoriya,” she said in a flat tone, grabbing the clipboard attached to his bed. “I suppose you had gone a bit too long without visiting. Almost two months.”
Izuku smiled sheepishly. “Hello, Recovery Girl. I really don’t know why I’m here this time.”
The old woman hummed. “It is because of your heat.”
Izuku blinked. “My…heat?”
“Your first heat, I assume.”
He shook his head. “But…I’m not…”
“It is quite rare for omegas to present so late,” she acknowledged, making her way to the side of his bed to prop herself on a rolling stool. “But you did. Congratulations.”
Izuku gaped at her age-carved face as his entire reality was flipped upside down.
He was…an omega?!