Since I know people will ask... this is a How to Train Your Dragon cross with MHA, with a slight twist.
The USJ was supposed to be a basic training exercise. Simple, routine... a way to show them another aspect of being a hero besides fighting villains.
But now, now Izuku was staring down an abomination that was about to kill a man he deeply respected for his realism. Aizawa-sensei was in bad shape and about to be killed. He didn't think too hard about his next action.
He roared, the sound an almost physical thing. He could feel the way his throat constricted from pain.
It caused the villains within range to fall back from the sheer force of the sound.
Izuku only had a split second to register the hand coming towards him fast. His instincts told him that being touched by the hand was a very bad idea.
It took all of five seconds to charge a quick and dirty plasma blast. The villain screamed in agony at the damage done to his body, though his hand was mangled it was still salvageable.
"NOUMU, KILL THAT KID!" shrieked the villain.
Izuku's battle instincts were on overdrive, uncaring of the unofficial rules drilled into him and his kin at an early age.
Izuku dove to the side, avoiding the hand attempting to swipe at him. To the shock of everyone but himself, his back bulged for a moment, before a pair of leathery jet black wings fanned out fully formed. There was a second rip as a long black tail flowed outwards, allowing him to keep his balance. His arms seemed to ripple a bit as scales formed, creating protective armor. His eyes narrowed, becoming serpent-like and dilated to adjust to the new influx of light.
He roared again, this time the sound was ten times stronger. However the monstrosity didn't back down.
A clawed hand lashed out, causing massive injuries that would have proved fatal if the thing didn't have regeneration capabilities. It attempted to tackle him, only for Izuku to take flight without a second thought and avoid it with ease. He leaned his head back, and a second plasma blast slammed into the villain, almost taking out it's head. Izuku didn't hesitate, and shot off two more in rapid succession before it could recover.
The Noumu crashed to the ground, dead from the sheer amount of damage done to it's brain. It's body couldn't keep up from the blast damage.
"Problem child, what the fuck?" rasped Aizawa.
"Cheater! You damn cheat character!" shrieked the villain as he was forcibly dragged off by his partner.
Izuku cautiously landed, his scales fading back into normal skin and his eyes cautiously returning to something a bit more human. His wings flexed a bit, before he stretched and allowed them to fold back under his skin. His tail swiftly retracted, though there was an embarrassing hole that he quickly pulled his shirt out to cover up.
"I AM HERE!" announced All Might, though it took him several seconds to register the awkward silence. "What happened?"
Izuku didn't bother to try and talk. He knew from past experience his throat was going to be soar as hell for the next few days. Instead he scrounged around for something to wrap around his waist to better cover up the hole in his pants.
In the makeshift recover tent...
"You're saying he transformed and defeated that villain solo?" said Toshinori.
Aizawa looked very beat up, but he nodded.
"I don't know how else to explain it. Midoriya basically took out the Noumu without any input from me. In fact my quirk wasn't even affecting his ability in the least."
Toshinori looked at Izuku, who looked more exhausted and resigned than hurt outside of a few minor injuries to his finger and his throat.
"Is there something you'd like to say, young Midoriya?" he asked.
Izuku's hands were rather fidgety and seemed to be making wild movements. Neither of them could understand it in the least.
Snipe, however, recognized it for what it was.
"He said he could really use some tea with honey and lemon for his throat right now. That or some ice," said Snipe. Izuku nodded fervently to that.
"How do you know that?" asked Aizawa.
"He just said so," said Snipe as if it were obvious. He gave them odd looks.
Izuku made a few more motions with his hands. Snipe gained an expression of understanding.
Aizawa looked between the two oddly.
"What did he 'say' this time?"
"He said that he didn't think either of you knew ASL, or American Sign Language," translated Snipe helpfully.
"How do you know it?" asked Toshinori.
"Sometimes I can't verbally communicate with a partner, because it would expose them to a villain. So I learned how to sign instead and taught my regular partners or side kicks how to sign as well for security reasons. I can't imagine why a kid would need to learn it, since from what his file said Midoriya isn't deaf or in contact with someone who is," said Snipe.
Izuku's hands moved again. Toshinori and Aizawa looked at Snipe expectantly.
"Signing is faster than writing, and it only happens when he uses certain attacks without adequately preparing first. He just needs a few days of rest and something to ease the pain in his throat and he'll be good as new by the end of the week," translated Snipe. Izuku gave him a thumb's up.
"Why not let Recovery Girl use her quirk on him?" asked Toshinori.
Izuku sighed, though he winced slightly from the stress it put on his throat.
"His throat muscles need to learn how to adjust to the aftereffects naturally, and he doesn't know how bad the others did so he wants her to save her energy for them in case they need it," translated Snipe. "That and his mother already knows how to handle this."
"Yes, about that...why did you tell me you were quirkless?" asked Toshinori, somewhat hurt.
"Not a quirk, also too complicated to explain right now without permission," translated Snipe.
"Permission? Permission from whom?" asked Aizawa.
Izuku winced. Clearly he couldn't tell them... figuratively speaking...without speaking to an outside party. Considering the recent attack, this could prove a major issue.
Izuku found himself staring down not only All Might, but the principal, Aizawa and Snipe...mostly because his throat wasn't fully recovered. Snipe had agreed to act as translator, because he was the only teacher in UA who could read sign language fluently.
"Young Midoriya... why didn't you tell us about your quirk?" asked Toshinori, breaking the ice.
"Not a quirk," rasped Izuku. He could talk in limited amounts, but he would still need a day or two.
"Then what is it?" asked Aizawa pointedly. "And why didn't my quirk work on it?"
Izuku thought about how to phrase this. Considering he was attending UA, odds were he'd be getting a lot of attention for their kind soon anyway.
"My mother was human. My father...is something else," said Izuku carefully.
"Something else?" said Nezu with interest.
Izuku looked at Nezu pointedly.
"Animals have better instincts than humans. What do yours tell you about me?" Izuku asked.
Surprised to be put on the spot about this, Nezu blinked. He normally tried to play off his status as being an intelligent animal with a quirk that placed him in the same category as a 'being' rather than a 'human'.
But that didn't mean he was ignorant of his own instincts, which as Izuku pointed out, were superior to humans.
Nezu observed Izuku, not as a student but as an animal would. And almost immediately flinched. To be fair, he had no prior close contact with the child before this point.
"You're a predator...a potential alpha. My instincts are telling me to be extremely wary of your presence and not to wander in your territory," said Nezu quietly. It was very discomforting.
Izuku, rather than be offended or upset by this statement, merely nodded as if he took it as a given fact.
The humans, however, were oblivious to the danger Nezu could very clearly sense from the child.
"Your father's quirk is listed as fire breathing," said Aizawa in discomfort.
"Because it was easier to explain his slip ups as a quirk than to tell people the truth. Those without quirks are automatically slated for training, because they have the highest chances of being less than human," said Izuku.
"Less than human?" repeated Toshinori. He did not like the sound of that.
Izuku knew that he wouldn't be able to adequately explain this, especially with his throat being so damaged. So he went for the visual demonstration instead.
He had made sure to pack extra clothes, for obvious reasons.
The sound of his shirt and pants ripping echoed in the room. The black wings flexed for a moment, before covering him in a protective coccoon. Scales rippled down his body, and he grew to almost the same height as All Might in his hero form.
When the transformation was over, and it was clearly well practiced, the teenager was gone. In his place was a black scaled dragon with green eyes.
The sheer intelligence behind his eyes was almost terrifying, in a way.
"Young Midoriya?" said Toshinori, concerned. Some people with animal quirks had trouble controlling their instincts.
Izuku snorted, and stood up on his hind legs. He made an odd rumbling sound in his throat, though it was clearly still a little sore.
"Fascinating!" said Nezu, and he meant it. "May I?"
Izuku went back on all fours and allowed Nezu to examine him. The wings were as long as he was tall, and it was obvious from looking at them that Izuku had trained his muscles to handle sustained flight. The tail flattened out to have almost rudder-like fins to help move in the air. His ears moved this way and that, almost like a cat's. The part that amused Nezu the most were his teeth. They were retractable, and he looked almost toothless when they hid inside his gum-line.
"I assume you know how to turn back?" asked Nezu.
Izuku picked up his bag with his teeth, before calmly walking into another room. A few minutes later, he came out in clearly different clothing considering his previous outfit had been utterly shredded. His dragon form was similar to All Might's own transformation in that it was very hard on the clothes.
"So... the problem child is a dragon," said Aizawa.
"The Council said it was okay to give basic information, but I can't give you too many details," said Izuku.
"Council?" said Nezu.
"The (Izuku made a noise that sounded like a word, but none of them could understand what it was) are a threat to us. They know the legends are not myths. We have to hide in plain sight for safety reasons," said Izuku.
"What did you call them?" asked All Might.
Izuku repeated it, then clarified what it meant in a more normal language.
"I believe you would translate it as 'the hunters'. People who seek out those like me to use as mindless weapons. It's only recently that we started coming out of hiding," said Izuku.
And even then it was only because of a fluke after quirks had started to gain worldwide acceptance. It would be centuries before his kind could properly come out of hiding. They were too used to hiding in the shadows.
Nezu looked utterly fascinated.
"Do you have a classification for your dragon form?"
"Night Fury," said Izuku without hesitation. "Should have seen dad's face when he realized what type of dragon I had developed into."
"Why?" asked Toshinori.
"Because Night Furies are extremely rare, and less than ten exist including me," said Izuku. "Almost all the training my dad had me do came from manuals that were left behind by others."
Izuku only knew there were others like him out there. He had never met them once, to protect their identities and his. After all, Night Fury were extremely prized by the Hunters.
"Does your mother know about this?" asked Toshinori.
"Dad told her when he found out I didn't have a quirk. About two years after I was diagnosed, I started the training to control my abilities," said Izuku. "Mom knows about us, but she was deliberately kept out of the more important details for security reasons."
"Question...why didn't my quirk work on you?" asked Aizawa.
Izuku gave him a flat look.
"Same reason you have no effect on the Principal. My dragon form is my natural form... Our human disguise only began about a thousand years ago, and there were a lot of missteps before we developed the ability to switch back and forth."
Hence why hunters often targeted the Quirkless. They had the highest probability of having dragon's blood in them. As a side effect, most dragons preferred to live in areas that were heavily policed by a large number of heroes...attacking them in broad daylight would get the hunters labeled as vigilantes or worse, as villains since they knew to stay in human form unless forced out of it.
Of course it didn't hurt that they had long since identified any substance that would effect either of their forms. Most had since been destroyed, or were made so heavily regulated that it made it harder for hunters to acquire it without setting off some major red flags.
At least he wouldn't have to hide his dragon-side as much. However it was still going to be a headache dealing with Bakugo. The explosive teen was going to be pissed learning Izuku had been hiding this sort of 'quirk' from him.
He was not looking forward to that.