Izuku was a late bloomer. His best friend, Katsuki, was the opposite. His friend's quirk came when he was younger than most, and it was more powerful than most at his age. He curated it, nurtured it, turned the power more and more powerful each passing day.
He did so by practicing on Izuku's body.
That was not his intentions initially, however. The scars were not the thought at the front of Katsuki's mind the day he showed his powers to the class. At the beginning, he still considered Izuku very much so his best friend. They got along with one another like pen and paper, salt and pepper, shoes and socks. However, the more powerful the power grew the more insecure Izuku found himself becoming. When would he, too, gain a power?
Katsuki began to wonder the same.
The more Katsuki grew the more Izuku simply - didn't. As his explosions grew larger so did his contempt for the boy. He could not figure out why his best friend was no longer an equal, why he wasn't keeping up. It angered him. He couldn't understand it. He wanted more than anything to put some powers into Izuku but couldn't find a way to do so. He wanted his friend to gain his powers.
It did not happen that year. Or the next year, for that matter.
The angrier Katsuki got the more scared Izuku got. The louder the explosions the louder the fear. He couldn't stand the way Katsuki had changed, how his quirk altered his brain and turned him from a friend into someone one could almost consider a fiend.
It was then Izuku made a promise to himself, he would not allow himself to do the same.
In second grade Izuku turned off his alarm clock from across the room. He absently swiped toward it, and though he did not touch it, it had silenced himself. It took him a few seconds before he bolted upright.
"Mom!" he called, his voice a mix of panic and excitement. "Mom I think I finally got my quirk!"
Inko opened the door quickly, her hair in a bun and a slightly stained apron swinging from the movement. Her eyes were bright, and her smile shined. However, her excitement weakened when she saw the look on Izuku's face.
He was staring at his hands with his eyebrows raised. All traces of excitement were gone from his eyes as he started to cry. Tears pooled in the corner of his eyes and traced thin lines down his cheeks. His chest convulsed as he held back sobs.
"Does this mean I'll become mean like Kacchan too?" he asked the empty air in front of him.