In Touching Spirit Bear, who is Peter?

The main character of Ben Mikaelson's Touching Spirit Bear is a teenage boy named Cole Matthews. To avoid going to jail, it is decided that he will spend a year on a remote island in Alaska, where his life and way of thinking start changing after he is attacked by the Spirit Bear he tries to kill.
It is clear that Cole has major issues, having grown up in a household with abusive and neglectful parents and created a criminal record for himself by age fifteen. We learn that before he was arrested this time around, he broke into and robbed a hardware store. Cole bragged about his break-in at school and was subsequently questioned by the police about the crime. Cole found out that Peter Driscal, a boy he had bullied before, was the one who turned him in to the police. Cole decided to beat Peter up after school for revenge and eventually got to the point where he smashed Peter's head on the sidewalk. By the time other students were able to pull Cole off, "Peter was cowering on the blood-smeared sidewalk, sobbing."
Peter is extremely traumatized by the attack, as well as Cole's Circle Meetings, and he eventually attempts suicide. As the book goes on, Cole loses his uncaring attitude and realizes that he needs to make things right with Peter.