i don't usually make information of them i always have them in the head though, but i could try ^^ :
When he was 5-6 he was always picked at and bullied by a group of guys. They always made fun of his teeth (he was a cute shota then X3) when he was 6½ years old, he made himself a mask that was green with orange lines. when he came to school, the bullies started to tease him even more. they took his mask and threw it at the ground, mud and grass and made it as dirty as possible. the next day, he came to school with his dad's stolen bat, and a fresh new mask but with horrifying teeth on and beat the SHIT out of them!
the story is longer than this, but i though you wouldn't like it if it was too long