Karma

He had a shitty quirk. He could alter the force behind any impact he creates, but trying to hit harder just backfired in him hurting himself as well, so it was just a bad quirk that hurt the user if used to greater potential. And for this, he was bullied. Cool kid with a cool quirk, aiming to be a hero, putting him down for being a nobody. Bakugo syndrome. But he didn't give up! He kept training in secret. He lived just out of town, across a lil bridge over a steep cliff, in the woods. beautiful landscape, really. Parents owned a koi farm out there. And there, in the woods, he trained to master his quirk. And, well, he did. He got control of his quirk, fine control to no longer hurt himself, and could even use it on other forces hitting him now! Signed up to UA, got all excited, everything! Yes, even if his bully just laughed at him for even applying to a hero course. He was going to be a hero, everything was linging up for a great big future.

And then, his real chance to shine came. A smalltime villain was robbing a convinient store, wanting all the money they had. The bully was there, ready to put a stop to this, but he was too slow. Before he could even act, our little underdog stepped up and struck the villain, dealing an absolutely devastating blow without hurting himself one bit. He literally KO'd that villain! The bully could only stand there flabbergasted, shock turning to rage as he was one upped by that nobody.

Later on, after everything was handled with the cops and he was walking home, the bully caught up to him. It was on the bridge leading out of town, in the sunset. The bully confronted him, enraged that he just one upped him, stole the show. That he hid his power and lied to him. That he made him look like a fool. Our underdog wasn't having it, and stood up for himself. About time someone put that bastard in his place! An arguement broke out, push came to shove. And in his anger, the bully lashed out, quirk and all, claws meeting skin. As his face was cut to shreds, he staggered, and fell off the bridge, into the chasm.

This wasn't what the bully wanted to do. This was an accident. But as he looked over the edge, he just saw a motionless, mangled body on the rocks, blood washed away by the shallow river. Dead. He killed him. The bully really just killed him. Not knowing what to do, he told no one and just went home. Of course he was declared missing, but the bully knew nothing, or so he claimed. He got into UA whilst the cops searched everywhere. In the end, after months, the search was called off. A funeral was held, and slowly, the world moved on. The bully, with a heavy heart, swore to be better. Better, but not good enough to say the truth. He'd take this to the grave...

Our underdog, however, wasn't dead. His mangled body had been found and taken, and awoke elsewhere after many surgeries. Found by All for One's lackeys, no less. He was rebuild, a metal skeleton supporting him now that his body would never be the same. He was hateful now, for the life stolen from him, and for the fact his abuser went on to find success, never to face any sort of consequences. It would take a long time before he could relearn to walk with this broken body, longer before he could plan his revenge. But revenge he would have...