I think that Junior is the character who has demonstrated the greatest embrace of growth. Junior recognizes early on in the narrative that life on "the Rez" will not enable him to grow. He understands that if he wishes to grow, if that is something he values, then he has to pursue life outside of the reservation and go to school at Reardan. Growth means that Junior will have to surrender part of the "comfort" in doing what everyone else does and grow as a process. The end result of this is that Junior learns to embrace change and growth as part of his identity. Through this, there is an affirmation that being able to embrace the unknown through the love of growth is powerful.
In a way, I think that Rowdy also demonstrates being open towards growth. While he has been steadfast in his refusal to go to Reardan and was fairly angry at Junior for leaving, the ending of the novel is one in which he, too, has made peace with growth and how human identity is predicated upon individual maturation. Rowdy making peace, to a certain extent, with Junior's choices displays an openness towards growth and change. The playing of the basketball game between both friends shows that no matter what, their friendship will grow and their bond will mature as time passes. In this, there is not an anger over the past, but an embrace and openness take towards growth.