How does the main character change throughout the book? What causes those changes?

Cole begins to change after he is mauled by the spirit bear. The real changes happen when he visits the island for the second time. Cole is much more receptive the second time around. Cole has sold all his belongings for another chance at redemption. Cole has begun to accept that he needs to change. He begins to tap into his rage as well as understand that he is part of a greater circle of life; he can add to it or seek to do damage.