YOU WILL BE LOST IF YOU BEGIN READING THE STORY WITHOUT READING THE DESCRIPTION!
You are an anti hero. You are too lazy to commit to villainy or heroism so you chose neither. You could've just been a normal civilian, and you were, until you turned three, but then you got bored and decided to wander off into your dads armory. He took this as a sign and then just gave you up to a weapons instructor. You were entertained with learning new skills but then you got bored again and decided to put those skills to work, by fighting, and killing, your parents. The fight was fun, but it was short. You were bored again. You decided that you liked fighting and you liked challenges so you took up street fighting. It was only mildly entertaining, until one day when someone cheated. That moment something hit you. It was what you needed for the longest time. A real, unpredictable challenge! It was thrilling! You then sought out the most twisted, low, dirty, immoral scumbags and challenged them and took them out one by one. You didn't always win. You loved loosing. You loved the thrill of being able to get stronger, the challenge. One day, you had the pleasure of taking on a good guy, not a real hero, but one of tinnier, weaker ones. You lost, over and over again. You became insistent upon learning alongside him. You were taken in and trained to be a hero, or at least a side kick. Once you could beat your instructor in a real battle you got bored. So went on doing whatever you felt like, until you were tracked down by him. He gave you an invite that looked like fun.
I got carried away with the description... By the way I won't be referencing episodes on a regular basis, they might just come up every once in a while, this isn't a line for line retelling. You already know the story how much of a difference would one character make.