This short story, first published in 1960 in the Atlantic Monthly magazine, focuses on the troubled relationship between two young boys: the narrator and his mentally and physically disabled brother, Doodle ("The Scarlet Ibis Characters," 2016).
Here the narrator describes how his brother got his nickname:
When he crawled, he crawled backwards, as if he were in reverse and couldn't change gears. If you called him, he'd turn around as if he were going in the other direction, then he'd back right up to you to be picked up. Crawling backward made him look like a doodlebug, so I began to call him Doodle, and in time even Mama and Daddy thought it was a better name than William Armstrong.