I was bullied when I was a kid. It changed me drastically, made me shut down in my own world and give me the ability of not trusting anyone, it made me 'stronger' to the point of emotional numbness. What Kyrielle said about girls being wolves is very true, though curiously, the most cruel words someone ever said to me came from a boy's mouth.
Anyway, when I was in my early teens, I changed school. Then, the roles reversed. It's not a part of my life that makes me very proud, but I can say that... somehow I understand bullies, because I had been on their side once. It's something very different, and maybe the others didn't see with the same depth I did, but, believe me, bullies are to be pitied too.