Chapter Text
Izuku knew Kacchan like the back of his hand. They'd been in each others' orbit for so long that he knew which way Kacchan was gonna move before he'd even twitched in that direction.
That's how he knew that Kacchan was going to enter a nesting frenzy.
It started with the people around him. They inadvertently started...attending to him. Making sure he had enough hot sauce for his lunch or holding his gauntlets for him and otherwise being up in his space in ways that drove the feral blonde absolutely fucking insane. The number of unplanned explosions per day rose by at least 30%.
Then (and this low-key made him feel like a creep for noticing) Kacchan would switch out his normal clothes for super-similar omegan clothing. His all-black loungewear went first. His omegan loungewear looked identical, but Izuku could tell. It draped a little more loosely, and Kacchan looked a thousand times more relaxed in it.
And third, just like right now, small things started going missing from the locker room. Easily replaceable things. A glove here, a head band there. The occasional towel. Stuff that was rarely missed except in the moment it went missing.
"Huh, I could have sworn I put my sweat band in here," Eijirou muttered, digging through his locker.
Izuku glanced back into his own locker, where he'd placed his gym towel. That gym towel was gone now. Just yesterday, Denki had asked them if they'd seen his undershirt.
He slammed his locker door and grabbed his things. If he caught up to Kacchan and stayed far enough back maybe he could—
Yep. Kacchan was waiting outside the girl's locker room anxiously, shifting from foot to foot. Mina poked her head out a moment later and handed him a bundle of clothing scraps with a wide grin.
"Thanks," he muttered.
"No prob. Just get Kyoka's shirt back to me as soon as you can, okay? I'll slip it into my laundry and say it was an accident."
Good system.
Nesting frenzy confirmed.
Izuku's stomach turned over. He had told himself a thousand times that this was it. That the next time Kacchan started nesting, he'd shoot his shot. They were third years, and Kacchan was easily his best friend. He was also the love of his life. But he was also the most desired omega at UA, bar none. Every time Kacchan hit pre-heat, courting gifts would flood the dorms and Izuku would watch in terror as Kacchan inspected each one and then crumple in relief when he turned them down. He couldn't wait on the sidelines anymore and wonder if Kacchan would accept him. He had to try, or else he'd miss his chance and regret it for the rest of his life.
And now, it was time.
"Mido?"
Izuku jumped out of his skin, whirling around to meet Eijirou's questioning gaze. "Hi!" he squeaked.
Eijirou eyed him in concern. It was understandable. He was kinda panicking. His heart rate was all over the place and he was so anxious that he felt like he was gonna throw up. Sure he had a plan, but he and Kacchan didn't have the best history. There was no reason to think this was going to go well, aside from the fact that they'd grown close. But maybe they were just meant to be best friends! Maybe he'd be ruining what they had if he—
"You okay dude? You look like you're about to puke or something," Eijirou said, inching closer.
"I'm fine," Izuku confirmed, still sounding like a squeaky toy.
"...If you say so, dude. But I'll totally walk you to Recovery Girl if—"
"DEKU!" Kacchan barked.
Izuku had never turned around so quickly in his entire life. He nearly fell over. This was already going very poorly. "Kacchan!"
"What the fuck is taking you so long, fuckface?"
"Sorry! Uh...did we have something planned?"
Katsuki looked at him like he was the stupidest person on the planet, and...fair. "We always walk back together. And it's Tuesday, shithead. We're supposed to review for English before we spar." Izuku's heart lightened. They did always walk back together. Izuku was the only alpha that Katsuki consistently tolerated. Except for Eijirou, who was already courting Mina.
"O-oh. Right. Sorry! Let's go."
He scurried to catch up with the blonde omega, who had already turned and started walking away. There was a spring in his step now. He could totally do this.
Izuku led Katsuki to his room, subconsciously determined to not disturb Katsuki’s nest. He ignored the raised eyebrow Katsuki gave him when he hit the button to the second floor. He did not ignore the quiet, pleased purring. He couldn't. But he also didn't react. He didn't have a death wish.
Indicator number four that Kacchan was heading into his cycle—he was much more open with his emotive reactions. Purring, growling, hissing, the works. In middle school, someone had called his purring cute and he'd thrown them into a trash can. Then he'd rolled that trashcan down a hill.
When they got into his room, he turned up the heat and pulled out blankets. Katsuki met him with a glare. "They're for me. It's cold in here," Izuku insisted. "You can have one, obviously, but I'll be freezing as soon as I change out of my uniform."
The glare softened, but the stare remained suspicious. "Whatever," he muttered, tossing his bag on the bed and shedding his jacket. Then he paused. "Fuck, I should change too," he muttered, shifting uncomfortably.
"You can borrow something," Izuku offered. It wouldn't be the first time. Kacchan grimaced, though—reminding Izuku that he'd be craving softer threads than the alpha could currently provide. "Up to you, obviously." The suspicious stare returned.
"Right. I'm gonna go change and put my shit away. Be right back." He grabbed his bag as he left.
When he hadn't come back in over fifteen minutes, Izuku realized that he was probably adding the pilfered items to his nest.
Izuku cast a glance at his closet, where the contents of his...probably excessive courting gift were stored. He'd spent months thinking about what to give him. Then he'd spent more months compiling his gift. Something to prove to Kacchan that he was loved and appreciated and desired for who he was—beyond and better than what everyone else saw when they decided to court him. Something to prove that Izuku was tailor-made for him.
He just hoped it would work.
"The fuck are you looking at?"
"WAH-chan!" Izuku yelped, turning wide, panicked eyes on the unimpressed blonde in his doorway. "Nothing!"
"...spastic fucking dork. Hurry the fuck up, we have shit to do."
Working with Kacchan made time move at breakneck speed. Or maybe that was just him, feeling like there was never enough time when it came to his childhood friend. He always wanted more.
Regardless, the evening sped by—from homework, to training, to dinner, then back to homework, until it was time for Katsuki to turn in. They were still bickering about the influence of old-school western media on modern heroics as Izuku showed him to the door.
"You're so full of shit," Katsuki barked, standing on the other side of the door.
"You'll do the research and in a week you'll be back here bitching about how Captain America was the prototype for All Might's heroic philosophy," Izuku warned.
"Fuck you. Go the fuck to sleep, you're going senile."
Izuku grinned at him. "You're only saying that because you think I might be right," he teased. Katsuki scowled. "Goodnight," he said, smile softening before he went to shut the door. Katuski threw his hand out before it closed all the way. "Kacchan?"
He was silent for a long moment, studying Izuku quietly. "You noticed, right?"
Izuku tilted his head. "Noticed what?"
Katsuki gritted his teeth. "That I'm nesting, asshole."
"Oh," Izuku replied, flushing. "Yeah."
The blonde bit his bottom lip, gnawing it for a moment before his shoulders dropped resignedly. "Scent me."
He couldn't help the fond smile. Kacchan hated asking for help. Demanding something though? Totally within his wheelhouse. He spared a thought for his courting gift, feeling much more confident that he was on the right track. "Sure, Kacchan," he replied, bringing his wrist up to brush the base of Katsuki's neck where it met his shoulder.
When Kacchan’s eyes fell shut, his eyelashes tickled the tops of his cheekbones. God, he was beautiful. With each pass of his wrist, the omega grew more relaxed—eventually letting his rumbling purr out into the air. Izuku withdrew, relishing the glassy crimson gaze as it refocused on him. "Don't wake up late, or I'm starting without you," Katsuki snapped half-heartedly.
Izuku smiled even wider. "Goodnight, Kacchan."
As soon as Katsuki was out of sight, Izuku texted Momo. He was almost ready, but he needed some help with the finer details, and no one did finer details like Momo.
>> Yaomomo
u awake?
Yaomomo <<
I am! Did you need something, Izuku?
He smiled fondly at her perfect grammar like he always did. No matter how comfortable they'd gotten with each other, she'd never eased up on her meticulous speech patterns. It was endearing. But also not something he had time to dwell on right now.
>> Yaomomo
yea I need ur help. its important.
Yaomomo <<
I'm on my way.