Who is Chase Wagner from Crank and what is their importance?

Chase goes to school with Kristina, and although he uses drugs, he tells Kristina that he has limits.... he won't let the drugs own him. Chase also chides Kristina for the frequency of her drug use, which is ironic being that he also provides her with drugs. Chase is, however, a much deeper person that we originally give him credit for.... this is evident in his offer to marry Kristina after he learns of her pregnancy, as well as to help her raise a child that is not his.