I have a little idea, what about adding a new tab to the CS where people list exactly why they bullied or teased the weird kid? It could add a little more to the character, and give motivation to the killer as to why he's hunting down his own class mates. It also breaks away from the typical and vague killers motive to kill. Saying he was bullied is an ok reason, but mentioning [i]why[/i] could flesh alot of things out. 

Then again, this is just a suggestion.