how?

I have an angry boy. He is very angry. 13 is a difficult age. I remember 13 very well. He tells me he doesn't care about me. Not that he hates me, he just doesn't care. He is angry and cruel to everyone around him. I don't know how to reach him. It is so frustrating. He will pick on someone just so he can punch them. The only solution that comes to me is to give the boy some space, but he will enter a room full of people just to instigate a fight. Testosterone sucks!