Why do you infer was the reason the narrator went back for doodle?

The narrator likely went back for Doodle out of a mix of guilt, love, and a sense of responsibility. Despite his earlier frustration and embarrassment over Doodle's limitations, he ultimately realizes that their bond transcends these feelings. The narrator's decision to return reflects a deep, underlying care for his brother, highlighting the complexity of sibling relationships and the impact of compassion in moments of crisis.