You know what? The chubby kid made a mistake: He walked away when the skinny kid was coming to. The tormented kid should've dropped him on the kerb, follow it up with a kick to the head to knock him out completely and then punch him on the ground so as to send a serious enough message that this is what is to happen to you if you fuck with me.
I used to be a bully when I was going to school and feel like absolute shit that anyone actually lost any sleep over my insecure ass. Let alone contemplate suicide.