Full Summary: Izuku was a late bloomer, he'd been identified in grade-school as an Omega but he'd never given off pheromones or had a heat cycle. He never saw the problem as he trained One for All and easily matched his Alpha classmates in strength and speed, never bothering to correct them when they assumed that he was an Alpha too. Even after graduating and starting work as a pro-hero he continued to see a doctor at his mothers' request but he was fine with being a defective Omega. When his body finally decided it was time, it couldn't have been at a worse moment. Post-Canon/Omegaverse. Yaoi. Rated M for a reason. I do not own cover art.
Chapter 1 – Omega
Izuku frowned as he chased the massive octopus-shaped villain through the wide-open streets of Tokyo. Civilians scrambled out of the way and into shops and restaurants as the criminal lashed out with elongating tentacles, spewing acidic ink from his mouth. He herded the villain through the streets until they came to a factory occupying a deserted area.
"These streets are mine!" It bellowed with vocals that weren't quite human. Izuku grimaced as he took his full-cowling to ten percent and kicked off the ground with just enough force to launch into the air without damaging the asphalt below him.
He flew upward, arching through the air, eventually adjusting his aim down towards the villain with his right hand. Izuku fired a volley of compact air bullets, hitting his target. Toxic ink sprayed out in a rushing torrent, coating everything in the immediate area and the villain deflated to a manageable size. Izuku changed his trajectory as he fell through the air and landed heavily on the weakened quirk user, forcing him to the ground.
"You're under arrest." He said sternly as he easily restrained the man on the ground, waiting for support to arrive.
He felt the air's temperature rise in a wave of heat as an incoming figure landed several feet away from him in a blast of fire and smoke. Of course Katsuki would show up first, Izuku finally noticing his surroundings. He had chased the criminal into Katsuki's neighboring sector.
Izuku smiled sheepishly as the smoke cleared. The Alpha stalked towards him, annoyance splitting his face into a toothy grimace. "The fuck Deku? Couldn't keep this mess in your own streets?" He kicked a black melted trashcan out of his way as he neared Izuku, helping him lift the villain from the ground.
Police and support heroes started filling the street. They handed the villain over before Izuku turned to face the ash-blonde Alpha. "Sorry, Ka-Ground Zero… I was trying to minimize the damage…" He started listing off all of the pros and cons of chasing the villain to this location. Katsuki cut him off after a few seconds with a loud snarl.
"Damn it, nerd! Quite muttering like a freak." Katsuki sneered at him as they moved to the side of the street, watching as a cleanup crew moved in to tackle the blackened melted street.
"It's just a fucking pain is all. You goin' to round face's party this weekend?" Izuku perked up at the mention of his friend. Uraraka's birthday was on Saturday. He nodded happily. He'd already gotten a gift for her weeks ago.
"Yeah, are you?" Izuku asked skeptically. Katsuki and the gravity manipulator didn't exactly get along.
"Not if I can help it." The Alpha muttered. Izuku snickered as an Image of Kirishima dragging Katsuki into the party, at least half-way through, popped into his head.
"Quit laughin', nerd. You oughtta ask her out already." Izuku froze at the Alpha's words and turned to face him with a tight practiced smile.
"I'm not interested." He said flatly. Katsuki's scarlet gaze slid to meet his as the Alpha smirked good-naturedly.
"She's one of the few Omega heroes our age an' you know she has the hots for ya', nerd. So why not?" Katsuki watched him with curious eyes, Izuku trying to shake off the weight of his stare.
"Why don't you ask her out then?" He quipped back. Katsuki would snarl back at his sly retort.
"I have taste nerd!" Sparks crackled off of Katsuki's skin. Izuku put his hands up to shield himself from the hot shower of materialized annoyance.
"I get it, Kacchan." Izuku teased the Alpha with his childhood nickname as he pushed his Quirk to the surface and dodged the smoking punch aimed at his face. "I've got to run. See you around." He smiled and waved to Katsuki before dashing down the street at the lightning-fast pace he'd become comfortable with. It was still the only noon and he didn't change shifts until six. He had plenty of time to save more people.
Izuku flopped face-first onto his bed, freshly showered and ready to sleep. He flipped off the lights and settled in as he replayed the events of his day, cataloging the details like he always did.
He frowned slightly when he thought of his conversation with Katsuki. He wasn't dense. It was plain for all that cared to see that Uraraka saw him as an Alpha and a potential mate. The reality of it was preposterous though. He felt he would never live up to her expectations.
He'd been tested like everyone in the fourth grade for his second gender and quirk. His mother had cried tears of miserable empathy when his results had come back as a quirk-less Omega, but as the years passed, his body easily put on muscle and he never went into heat or released pheromones. The only people who knew his secret were his mother, All Might, and Recovery Girl. He didn't want to be labeled as a freak, so he was content to just stay quiet when the people around him assumed he was an Alpha.
Katsuki's snarling face flashed under his closed lids and Izuku snickered slightly. He tried to envision what Katsuki's type of partner would look like and he kept coming up with ridiculous results. A sharp pang of emotion shivered through him as he realized that Katsuki would probably find someone someday.
He sighed and rolled to his side, struggling to get comfortable as his skin felt flushed and his mouth suddenly felt dry as the desert. Sweat rolled down his face and his eyes flashed open. What was happening? He felt sick to his stomach and his blood was running hot. For several long minutes, he shivered in pain before the symptoms left as suddenly as they had come on. Was that… his heat?
He grabbed his phone off the bedside table and made an appointment through Recovery Girl's online check-in. He would go see her before his shift started tomorrow. Something definitely felt strange just now and a pang of fear shot through him. He tried to ignore the feeling and turned over, forcing his mind to quiet down, and eventually falling asleep.
Izuku stepped out of the clinic feeling slightly relieved. Recovery Girl had been reluctant to admit that what he'd felt had been his heat, but she'd still given him a month's supply of heat suppressants just to be safe.
Her stern warning replayed in his head. "If you forget to take those and you go into heat, you'll be putting yourself and every Alpha around you in danger."
He read the label on the small pill bottle for the hundredth time 'one tablet twice daily with food', that was easy enough. He stuffed the bottle into his pocket and headed for his hero office. Maybe he had just overreacted to having a stressful day, but he would follow instructions just to be safe.
The rest of the week went by without incident, but Izuku was careful to avoid Katsuki's sector. He felt awkward about seeing the explosion master. He took his pills faithfully, but he'd started to wonder if he'd really just had a panic-attack and mistaken it for his heat. He hadn't had any other symptoms or issues so he shrugged the event off as a one-time thing.
Friday came in a flash and he found himself chasing small class villain all day. His legs ached from keeping full-cowling going for hours. He would stumble into his apartment hours later than normal and crawl into his bed exhausted, not bothering to eat or shower. The small bottle of suppressants forgotten on his kitchen counter as he slipped into blissful sleep.
The next morning Izuku woke to the sound of his phone buzzing incessantly next to him, but it was his day off. He grabbed it and answered quickly still half asleep; there might be an emergency. The voice that pierced his ears had him relaxing instantly though.
"Oi! Deku? Did I wake you up? Iida and I are outside your apartment! Did you forget about my birthday breakfast?"
Uraraka's soft teasing had him jumping out of bed and grabbing a set of clean clothes before heading to the bathroom. "Ah… no. I didn't forget. I'll be down in five, okay?"
"Alright, that's a promise!"
The call beeped and Izuku mumbled to himself as he looked at the time. He'd slept way past his alarm. He stripped and stepped in the shower, cleaning himself at record speed despite his aching muscles and slipped into the grey jeans and a green polo he'd grabbed on instinct without drying off.
He raced out of the bathroom, grabbed Uraraka's small gift from his bedroom, and stuffed it in his pocket before flashing to the front door. He swung it open to find Uraraka and Iida grinning back at him as the gravity user held up a pink stopwatch reading '4:20'. Izuku laughed as he stepped out to join them.
"You timed me?" He snickered as they left his apartment building and walked down the street. Uraraka smiled at him brightly and puffed up her chest.
"I've got to make sure you're not forgetting all your promises. You said five minutes!" Izuku blushed lightly in embarrassment as he started to apologize for sleeping in. He hadn't meant to forget their group breakfast this morning. He had just been busy. He was grateful when Iida held up a hand to stop his mumbling; a habit from their years at U.A. The raven-haired Beta had always been calm and collected in the face of Izuku's obsessive mumbling.
"No need to explain Midoriya. We are all busy with work. It is good to see you living the Plus Ultra life." He smiled at Iida and nodded his head in thanks. He watched as Iida stretched and relaxed, nearing Uraraka's favorite udon restaurant.
"Yeah, you guys have been doing great lately too." They talked with great animation as they went into the restaurant and took their seats. This was the usual routine for Uraraka's birthday. He and Iida would occupy her time for the day while the rest of the 1-A students set up a surprise party.
They had all kept in touch after graduating. Even requesting sectors and positions that neighbored each other. It had increased the safety of their part of Japan so much that the Hero agency had started doing the same with graduating hero classes after them.
So Izuku and Iida took the gravity user to breakfast followed by a day of shrine and park visits. Uraraka was still as frugal as ever despite providing her parents with a great lifestyle due to her work as a hero.
Iida stepped away to take a call as they moved from the gates of the last shrine on their list. Izuku waited patiently for what he knew was coming.
"Alright… If you're sure we're needed…. Yes… Goodbye." Iida turned to them with a serious expression on his face after hanging up the phone.
"We're needed for an emergency rescue." Izuku held back his smirk. That wasn't a new one. They had already used most of the excuses at least once.
"Well, let's go then!" Uraraka wasn't fooled but she smiled and jumped in place, knowing what was coming.
They took off through the streets, using their quirks at low levels since they were in civilian clothes. They still reached the destination Iida led them to in less than ten minutes. Izuku swallowed a small bubble of anxiety as he realized they were standing in front of a large building in the abandoned warehouse district- Katsuki's sector.
He didn't have time to dwell on the thought as Uraraka ran forward, breaking so many hero rules, and ripped the warehouse doors open with a gleeful shout. "Who needs saving?!"
Lights flashed from inside the building. A guitar riff ripped through the air over amplified speakers. Uraraka rushed inside as a rock and roll version of 'happy birthday' sounded through the air in Jiro's husky voice.
"Shall we join the rescue?" Iida spoke up from beside him and Izuku nodded. He might as well get a little drunk and enjoy the party.
They stepped inside and placed their presents on the table for Uraraka to take home later before joining the crowd of their old classmates and friends. Izuku smiled as Ojiro passed by them, offering up a colorful pink cocktail from the tray resting on his tail.
"Everyone went all out, huh?" Izuku said as he took a sip of the cocktail and smiled at the taste of strawberry that hid the potent tang of liquor.
"Indeed, Heroes never truly rest. It's nice to get together and let loose." Iida spoke as he surveyed the crowd and waved to Izuku. "I'm going to check on everyone."
He smiled as the Beta rushed off to make sure everyone was getting along and the party planning had gone smoothly. He downed his drink in a heavenly swallow and grabbed another as he headed towards the crowd of students chattering happily with Uraraka.
Izuku, talked, danced, and drank for more than an hour in peaceful bliss before the door slammed open. Kirishima's red hair poked through followed by a plume of smoke and an angry snarl.
"I can walk on my own, shitty hair!" Izuku swayed drunkenly as he watched Kirishima get blown through the doors, shaking off his arms as they smoked, but weren't damaged passed his hardened skin.
"Hey, dude! You looked like you were gonna' run. Don't get mad at me for making sure you have a good time!" Kirishima growled back as he grabbed a bottle of dark liquor off the drink table and took a swig before handing it to Katsuki who had stomped through the door behind him.
"Fuck, at least there's booze." The explosion master growled as he took his friends' offering and the two joined the crowd.
Izuku's chest tightened as he watched the blonde-Alpha snarl and laugh as he talked with the people around him. A small hint of salty smoke floating in the air. He didn't know why but suddenly his thoughts were torn. He didn't know if he wanted to run to Katsuki's side or in the opposite direction. His stomach wrenched as his head swirled with drunkenness.
He set his empty glass down and traced the wall of the building, looking for the bathroom. He needed to get away from the crowd. He was relieved to find a tile-lined room with three stalls, quickly stumbling into the closest one. He closed the door behind him and leaned on it as he tried to take slow deep breaths.
His legs shook and his eyes widened as heat spread out from his stomach in a violent wave, flushing his skin to the point of sweating in merely seconds. He gasped as his breath left him in a painful pant and sunk to the floor.
This couldn't be happening. His mind flew to his doctor's visit earlier that week. He patted his pockets desperately searching for the small bottle of heat suppressants before he moaned in defeated pain. He came up empty and an image of the prescription sitting on his kitchen counter next to the coffee pot flashed through his mind.
Shit, he'd been careless, reckless. He vaguely realized between surging waves of heat that he hadn't taken his pills since Friday morning. Guilt filled him as he struggled to think clearly. He dug for his phone and pulled it out, his hand shaking as he tried to hit the buttons to dial Recovery Girl. He dropped his phone and collapsed on his side, shivering violently under the heat rushing through him, struggling to stay conscious.
Katsuki moved through the crowd. He'd seen Izuku when he came in, but he couldn't find the nerd despite looking everywhere. The punk had been avoiding him all week.
He knew it the moment he'd seen Izuku fight a few villains on the news. They normally ran into each other a few times a week, the abandoned portion of Katsuki's sector making for a good area to subdue large criminals. More than once though, the power user had opted to use risky moves or change his strategy to avoid getting close to his sector.
It was the real reason he'd played along with Kirishima dragging him here. He wanted to know what the fuck was up. He hadn't meant to offend him talking about dating and shit. He just thought it was a waste.
Izuku was a fine specimen- an Alpha Hero like himself, but the man hadn't been in a relationship for as long as Katsuki had known him. He'd started to find it strange. Even he'd had a few one-night stands throughout the years to satisfy his urges. But the nerd was being a nerd and avoiding him so he meant to drag out his issues tonight, but he couldn't fucking find him.
"Damn nerd…" He growled under his breath eyeing the doors around the room as he searched for possible escape routes. Besides the front and back door, there was only one other escape with an artful 'Restroom' banner hanging above it.
He headed for the bathroom. Maybe the nerd had gotten wasted enough to be hanging over the porcelain throne right now. He swung the door open and marched inside ready to give Izuku hell, but he instantly froze as the air in the room hit him like a cement wall to the face.
Katsuki slapped a hand over his nose and mouth. Omega pheromones wafted from the stall in front of him in sweet tendrils of a warm wet forest scent. The instant animalistic desire to find the source of the smell and capture it as his own rushed through his senses, but he fought the urge. He growled in outrage and whipped out the suppressant shot he always carried jamming the needle through his pants and into his thigh as he cussed.
"Fucking shit! Who the fuck…?"
Heat flooded his cheeks as the shot didn't completely stop his body from reacting to the Omega pheromones, but his mind cleared and he slapped the stall door open, a shivering mass on the floor groaning at the loud banging it made.
In that moment Katsuki's mind almost exploded.
It was Izuku.
The nerd was curled up on his side, cradling his stomach. He shivered with every breath, his skin flushed and dripping with sweat. The sweet scent of Omega pheromones poured off of him in waves. Katsuki's mind raced, childhood memories, awkward moments at school, camping trips, and his conversation with the nerd earlier that week.
He was an Omega. Deku was a fucking Omega. The thought exploded into his mind with force and he stumbled backward, falling flat on his ass.
"Fuck Deku!" He quickly got his shit together, realizing the nerd was in a bad situation right now. He clenched his jaw as he inched forward across the floor to nudge the other man with his foot.
"You're a fucking adult Deku. How'd you end up like this? Where're your shitty suppressants?" He ranted and the nerd finally rolled onto his back and looked at him with a fogged emerald gaze as he tried to speak through his strangled panting.
"I… I don't… h-have them." Izuku reached for Katsuki's leg and he jerked it out of reach, pushing to his feet as he tossed the empty shot case in his hand towards the trashcan. Damn it. He'd have to help deal with this somehow. Deku needed to get out of there before more of their class realized what was happening.
He bent and pulled Izuku from the floor, growling as the nerd groaned and his body went limp against Katsuki's side. "Shit, Deku?! Are you fucking kidding me right now?"
Harsh panting was all that answered him. He cursed under his breath as he hefted the other Hero's weight more heavily onto his shoulder and dragged him from the bathroom, pacing down the warehouse wall and out the back door, hoping that nobody would notice them.
He made it outside and sucked in a breath of cool air. He didn't know Deku's address. He never visited anyone at their homes, so he didn't care to learn. He grimaced as he decided to go to his house. He could figure out what to do once they were out of the streets.
With his mind made up, he shot his free hand down and let his quirk ignite, catapulting him and his passenger into the air. Fucking nerd better thank him for all this trouble later.
Katsuki landed in front of his flat a few minutes later, breathing hard from using his quirk without his equipment. He shoved his door open and tossed Izuku onto his couch. He eyed the green-haired man in disbelief once more.
It was shocking that Deku was an Omega. Nothing about his body was soft. He'd never taken regular time off from school or work. How the fuck had he hidden it this whole time?
He scrubbed a hand roughly through his hair as he pulled out his phone and sat on the arm of the couch, cussing when he couldn't think of anyone to call. Who else knew about this? The nerd had obviously been keeping it a secret.
He reached over and grabbed the other man's shoulder, shaking him roughly back to consciousness. "Wake up, nerd! Who the fuck can I call to come get you?"
Izuku's eyes slid open and he looked up at Katsuki with a fogged gaze before he turned into the Alpha's hand gripping his shoulder. Inhaling deeply against Katsuki's wrist. "… smells nice..."
His mumbled words had Katsuki dropping his phone, jumping up from the couch, and wrenching his hand away. A tight grip caught his arm and One for All crackled against his skin as Izuku jerked him back down.
"Fuck, let go Deku!" He growled as Izuku held his forearm in a crushing grip and buried his face against Katsuki's chest. The scent of the forest, rushing up to meet his senses. He could blast his way out of the hold, but he'd be destroying his own home and the nerd probably didn't even know what he was doing. Katsuki chocked back a snarl when he felt Izuku's hips grind up against his. Katsuki pushed himself up enough to look Izuku in the face.
"Do you fucking realize who you're humping, nerd?" He growled down into the other man's face, trying to bring him out of his stupor. He hadn't had nearly enough liquor to just go along with this.
Izuku just moaned softly and pressed his hips into Katsuki's harder, wrapping his free arm around Katsuki's shoulders so he could pull himself up to lick at the Alpha's throat. "…Kacchan…please…?"
The soft words in his ear and the enveloping scent of Izuku's pheromones had his face burning. Heat raced down his body. He was fucking hard. He bit the inside of his cheek as Izuku pressed against him once more and a war raged inside him. He was screwed.
*** Thank you for reading the first chapter of this new story! Look forward to frequent updates and please leave a review!