Who is Bobo Kelton from The Rag and Bone Shop and what is their importance?

Bobo Kelton is the school bully. One day, in the cafeteria, Bobo pushes Jason, after which, Jason turns around and hits him with his fists. The prior day, Jason witnessed Bobo pushing one of the girls up against her locker, whispering something in her ear and twisting one of her breasts. The girl was unable to do anything but shake her head no.