"Are you out of your damn mind, Deku?!" Katsuki loudly asked, his deep voice resonating in the classroom.

"Kacchan, not so loud..!" Izuku promptly said as he gave worried glances around them, checking if someone had heard Katsuki. It was their first day at UA and Izuku would prefer not to draw people's attention on them this soon, especially when what he was currently talking about was such a touchy subject.

Katsuki understood this and processed to whisper-yell instead of shouting aloud. "You fucking hid the fact you're an omega to UA?!" He repeated what Izuku had just confessed to him, shock and incredulity filling his voice.

Izuku timidly lowered his emerald eyes at the accusative tone of the blond alpha. "Yes..." He hesitantly murmured, before explaining himself further. "There isn't any omega in the hero's course, what if they hadn't accepted me if they had known?" He pointed out.

Being a hero was his dream since forever but, of course, he had to be an omega. Actually, he had always thought he would be a beta. He had presented as an omega quite late, during the end of his last year in middle school. He had suddenly found himself in heat in the middle of a street and, if it hadn't been for Katsuki who had saved him, Izuku would have probably gotten raped by some stranger.

It had actually been from this point on that their relationship had started to relatively improve. Katsuki was the only one to know about Izuku's second gender with his mother. Not even All Might knew about it. After having saved Izuku once, Katsuki had started to get protective of the omega and had even decided to make it a point to protect him...

Blame it on his instincts or something else, he didn't know and didn't care.

"It's never gonna work." Katsuki sighed. There was no way Izuku would be able to hide the fact he was an omega to a whole school during several years. UA had a dorm system, it was impossible that nobody would notice anything.

"I use scent blockers, people will just assume I'm a beta..." Izuku began but Katsuki quickly cut him off.

"You're too cute to be a beta." The alpha bluntly stated.

And it was the truth. Izuku was a real beauty. His big emerald eyes were simply beautiful, anyone would get mesmerised by the two pools of green if they looked at them for too long. His eyelashes were long and dark, his lips were an attractive pink and plump and the few freckles that were covering his cheeks gave him an absolutely adorable look. Even his messy green curls looked perfect. They seemed so soft people only wanted to touch them.

Actually, Katsuki could already see some of the alpha students looking at Izuku from afar. Even if they didn't know he was an omega, they were instinctively drawn to him...

"And your heats are fucking unstable, Deku." Katsuki added.

It was by far the most problematic point. It probably was because it hadn't been long since Izuku had presented as an omega, but his heats were completely unstable. They would suddenly strike without any warning at any possible time, regardless where or with who Izuku was.

What's more, Izuku became completely controlled by his omegan instincts when he was in heat. The only thing that mattered to him during these moments was to find an alpha and mate with him, nothing else. He became a completely different person and would then forget everything once he had gotten off once...

It was extremely dangerous.

"I found new suppressors, they work..." Izuku timidly said, his words earning a scoff from Katsuki. "How many times did you already give me this bullshit?" The alpha rudely asked.

Izuku lowered his emerald eyes at Katsuki's words. He knew Katsuki was right, suppressors never worked on him, but, even so... "Please, Kacchan. I really want to be a hero." The omega timidly murmured. It was his dream and nothing would prevent him to achieve it, not even his second gender.

"You're gonna end up in heat in the middle of a school full of alphas!" Katsuki suddenly whisper-yelled. He didn't understand how reckless Izuku could be. It was serious. UA was mostly filled with alphas and, if Izuku ended up in heat there, Katsuki didn't even want to imagine what could happen.

"I won't." Izuku answered. "And, even if it happens... you'll help me, right?" He asked, a soft blush appearing on his cheeks as he looked at Katsuki, his beautiful emerald eyes filled with hope.

Katsuki sighed. "You know I will." The alpha said. "I always do."

Since the first time he had saved Izuku, Katsuki had always helped Izuku during his heat. He would take care of the omega and help him get off. He never went too far. He would only jerk Izuku off or finger him until he would reach his climax.

Once Izuku had orgasmed, his heat ended and the omega usually didn't remember anything of what had happened. He only knew Katsuki had taken care of him and it was all he needed to know. He trusted Katsuki.

"Kacchan..." Izuku began, his voice filled with gratefulness and unspoken feelings, when someone suddenly interrupted them.

"Excuse me?" A girl with large round eyes and shoulder-length brown hair talked to them, another girl with pink skin and two thin, pale yellow horns protruding from her head standing next to her. By the lack of pheromones coming out from the two of them, they seemed to be betas, both wearing a friendly smile on they face.

"Hi, I'm Ochaco." The first girl said. "And I'm Mina!" The other happily exclaimed. "Do you guys know each other?" She asked.

Izuku was surprised people were talking to them. The fact he had been whispering with Katsuki until now on had surely dragged attention and aroused others's curiosity. It was evident to anyone Izuku and Katsuki both knew each other since before UA, or they wouldn't be having a secret conversation right from the first day...

"Oh, yes." Izuku answered. "We know each other."

"Are you together?" Mina suddenly asked out of nowhere, her question triggering a dark blush to spread on Izuku's cheeks.

"Mind your own fucking business." Katsuki rudely snarled. He didn't like when people he didn't know talked to him, even less when it was to ask such private questions like this.

"Kacchan!" Izuku gasped. "Sorry. We're childhood friends." He told the two girls with a sheepish smile, hoping Katsuki's blunt answer hadn't made them upset.

But Mina and Ochaco only chuckled in response. "I see, you seem quite close." Ochaco stated with a giggle. "Hey, you're a dominant alpha, right?" Mina then unexpectedly asked Katsuki, the pink skinned beta looking at the blond alpha up and down.

Dominant alphas were the most powerful alphas and it was quite obvious Katsuki was one. He was incredibly handsome, with his perfect features and captivating crimson orbs. His pheromones were strong and imposed submission. The whole atmosphere surrounding him oozed strength and dominance, even arrogance.

"Right." Katsuki carelessly answered. He was used to being asked this question and couldn't bother less about people's opinion about the fact he was a dominant alpha. He knew it dragged attention but he didn't care. He just liked knowing he was superior than others.

"And you?" Ochaco turned to Izuku. "What is your second gender?" She asked.

Izuku felt his heart start to race inside his chest at the question. He inevitably stiffened, his heartbeats increasing more and more as he tried hard to stay calm and not panic. "I'm a beta..." He managed to say in what he hoped was a confident voice.

"You don't look like a beta." Someone unexpectedly spoke up.

Izuku's heart jumped inside his chest as he promptly turned around to see who had talked, his eyes landing on an alpha with red hair and spiky teeth, one small scar above one of his red eyes. Another guy was next to him, this one having relatively short blond hair with a black lightning-shaped streak on the left of his side fringe. He had bright yellow eyes and seemed to be a beta.

"Right, I never saw a guy this pretty!" The blond haired guy exclaimed.

It looked like their conversation was attracting people's attention on them since more and more students were starting to join them, all eyes now focused on Izuku.

"Your face is so adorable, like an omega's face!" What had to be an invisible girl eagerly described.

"He can't be an omega. He wouldn't be in the hero course, otherwise." A serious looking alpha with short dark blue hair and rather square eyes matching his rectangular glasses pointed out. It was simply unthinkable that an omega was in the hero course. It had never happened since all the years UA was created.

"Right..." Izuku timidly agreed.

The omega was getting quickly uncomfortable and stressed out by all the attention he was suddenly getting. Hearing people saying how pretty he looked was maybe nice, but it mainly scared him that they would understood how he was in reality an omega. He really couldn't afford being found out right on the first day...

"You're all so damn noisy. I'm getting tired of hearing you fucking squeal right next to me." Katsuki suddenly grunted.

"Let's go, Deku." He said as he grabbed Izuku's hand and started to drag the omega away from all the people surrounding them, unexpectedly leaving the classroom all of a sudden.

Izuku could finally breath. "Thank you, Kacchan..." He gratefully murmured, knowing Katsuki did what he had just done only because he had noticed Izuku getting uncomfortable. Katsuki was always here for Izuku when needed.

Katsuki simply nodded to acknowledge Izuku's thank, before turning to look at the omega. "I told you that you were too pretty to be a beta, Deku." He said.

"I give you only one week before they'll figure it all out."

So, this was the first chapter of Unstable Heats. I hope you liked it!

I'll try to update regularly so that the story advance quickly. Don't forget to vote and comment :)

As usual, since I'm actually french, don't hesitate to tell me if you see any mistake. I'll fix it and it'll help me to progress!