What happens to Peter and Cole when they're on the island together?

Peter has a lot of anger and resentment. He feels a victim and has trouble empowering himself. Cole is, by this time, much more self-aware. He gives Peter space to vent his anger. Cole even lets Peter hit him. Peter pesters Cole about things like the spirit bear being real. Eventually Peter and Cole begin a dialogue, a beginning for both boys to truly let go of the pain. Check out chapter 27/28.