The protagonist of The Absolutely True Diary of a Part-Time Indian by Sherman Alexie is Arnold "Junior" Spirit, usually referred to as Junior. Based on the thinly-fictionalized experiences of the author, this is a coming-of-age story about a Native American boy growing up on the Spokane Indian Reservation and having to negotiate the conflicts between white and Indian society, balancing his desire for an education with his loyalty to his tribal heritage.
The first example of his personal growth is when his dog Oscar gets sick and his family cannot afford to take him to the veterinarian. At first he is angry about the way his family seems to accept the need to kill Oscar, but when he sees his father crying, he begins to understand that the problem is not that his father is cruel, but rather that extreme poverty makes it impossible to save Oscar.
One major example of his personal growth is his decision to attend a white school outside the reservation. Although he knows that he is likely to face racial discrimination from the white students and that he will also be ostracized by many of his Native American friends, who regard this as a betrayal of their culture, he nevertheless gathers up the courage to do what is needed to develop his intellect.
Another example of Junior's personal growth is his decision to make friends with Gordy. It marks a point when he begins thinking of the white children in the school as people he can interact with comfortably on an individual basis, who have hopes and fears just like his own.
When he draws a cartoon for Rowdy, we see him growing up in a way in which he begins to realize that what he really wants is not to become exclusively part of white society, despite his concerns about the alcoholism and violence on the reservation. Instead, he wishes to belong to both cultures and he is developing the strength to reach out to his former friend.
After Junior has been attempting to conceal his poverty, he is forced to borrow money from Roger, the star high school basketball player whom Junior has always considered a racist. Not only does Roger loan him the money, but on discovering Junior's issues with transportation, he offers to help him out. It is at this point that Junior has his most important epiphany, realizing:
"...If you let people into your life a little bit, they can be pretty damn amazing."