In "The Red Convertible," the disconnect between Lyman the narrator and Lyman the person who is now "walking everywhere" instead of driving is visible in the first paragraph:
I was the first one to drive a convertible on my reservation. And of course it was red, a red Olds. I owned that car along with my brother Henry Junior. We owned it together until his boots filled with water on a windy night and he bought out my share. Now Henry owns the whole car, and his younger brother Lyman (that’s myself), Lyman walks everywhere he goes.
(Erdrich, "The Red Convertible," Google Books)
The paragraph sets up the location (a Native American reservation), the car itself, and its relationship to Lyman and Henry. Because of the eventual fate of Henry and the car, Lyman's feelings and thoughts are affected, and he refers to himself in the third-person to show how disconnected he is from the entire ordeal. Lyman feels that Henry has been so affected by the war that he is a different person, and by the end of the story, with Lyman's failure to reconnect and then his failure (if it was really a legitimate attempt) to save Henry's life, he feels as if he has become a different person as well. The Lyman who owned the red convertible with Henry before the war is as gone as the Henry who left to fight; he walks everywhere because he "sold" the car to Henry entirely.