Why does Paul agree to testify against Erik? Try to think beyond the obvious answer of ‘Erik bullies him and Paul doesn’t like him,” think instead about Paul as a character.

Paul's decision to testify illustrates his growth as a character and an individual. He now understands his fear and refuses to hide from it. His decision isn't based upon himself or what he suffered, but rather, Erik's propensity for violence..... his indifference to others, and the dangers he presents. In providing the authorites with his statement, Paul is able to confront his past, his parents' complicity, and in essence, free himself to be a part of his community.