World War II interrupts the life Tayo had for himself, just like it did a variety of other white and Native Americans, forcing him to mature on the battlefield amidst the cold temperatures, death, bombings, and destruction of war. Upon returning, most of the Native American men drown their ire-filled trauma in alcohol.
Tayo, however, is a little different in that he is more depressed than angry. For a life time, Tayo has wished for acceptance from his family due to his mixed heritage of white and Native, yet he is gray in the sense that he doesn't appreciate either side. He cannot see the point of the white man's war and he doesn't truly appreciate the power of old Native tradition and stories.
This changes once he learns more from the medicine men Ku'oosh and Betonie. He's forced to trace back his roots, his parents and his upbringing, and even the times long before that where Native American myths were common knowledge among their community. These end up being the sole thoughts of Tayo that feel truly coherent, and he realizes this as a source of healing. Learning from these stories and the culture that is in his blood forces Tayo accept that these traits found in the myths are who he is as a person because they make him feel at home for the first time. It flows through him so smoothly without being impeded, leading us as readers to infer that this is natural for his development and who Tayo is as a person, even with his mixed blood.