I think that although the narrator was responsible for Doodle’s death, he should not be fully blamed for it. The events leading up to Doodle’s death—especially the narrator’s impulsive abandon of Doodle—were caused by the narrator’s feelings of shame and resentment, and this makes Doodle’s death his fault. However, his actions were not influenced by his true feelings about his brother; they occurred in a moment of heated emotions and shame that quickly abated. Because a weakness in all humans is not having control over one’s feelings, I don’t think the narrator was fully responsible for his actions at the time. (Had the narrator been intentionally wishing Doodle harm at the time, my feelings about his actions would be different.)
The narrator
The narrator