Describe the relationship between Arnold and Mr. P in The Absolutely True Diary of a Part-time Indian?

At first, the relationship between Arnold and Mr. P is
very tense--Arnold is angry that Mr. P is still using the really old textbooks in
class.  He feels that Mr. P is not giving him and the other students a quality
education.  Out of anger and frustration, Arnold throws a book at Mr. P.  But Mr. P is
not mad at Arnold for this incident; instead, Mr. P goes to Arnold's home to talk to him
about school.  Mr. P confesses that he has done little over the years to challenge the
poor education that the students receive on the reservation.  Mr. P tells Junior that he
knows that he is smart and that he should leave the reservation to follow his dreams. 
Junior respects Mr. P for admitting his faults and encouraging him to
succeed.