Paul wants to be able to deal with Mitchell, as his sister is able to. Paul says " But Cassie was not only beautiful, she was tough, smart, and just a bit cocky," meaning that she is more than just a pretty face. Paul also says he has a problem with Mitchell ("At first I just tried to stay out of Mitchell's way, but that didn't solve the problem.") Paul is trying to deal with that problem, and that is why he talks to his sister.
