In "The Scarlet Ibis," the narrator recounts events that occured in the past. When the narrator is six, his little brother is born. He is born in a caul, meaning a membrane surrounded his head, so everyone expects him to die. However, the little brother lives, and when he is three months old, their parents give him the name William Armstrong, of which the narrator does not approve.
The narrator is extremely upset that his little brother is disabled; he had high hopes that his sibling would be able to run and jump and play with him. When his mother suggests that his little brother might not turn out to be "all there," the narrator is even more upset; however, when the baby stares right at him and smiles, the narrator knows that he is "all there" after all.
When the baby is two years old, he learns to move around and crawl by himself. As soon as he does, they decide they need to give him a new name that fits him better; they settle on Doodle, because he only crawls backwards, just like a doodlebug. Only their Aunt Nicey does not think this name is fitting; she believes that he should be treated with more respect, since caul babies might turn out to be saints.
Their father builds Doodle a go-cart to get around in, and the narrator is forced to take Doodle with him everywhere he goes. He takes him to a place they call the Old Woman Swamp, and Doodle begins to cry because it is so beautiful. From that moment on they go down to the swamp often and adorn themselves in wildflower crowns and necklaces. At other times, though, the narrator is mean to Doodle; most notably, he takes Doodle to see the coffin that was made for him when everyone thought he was going to die, now sitting forgotten in the barn. He forces Doodle to touch it, and threatens to leave him alone with it if he does not.
When Doodle turns five, the narrator is embarassed by having a brother who cannot walk, so he decides to teach him. It takes a lot of practicing to overcome Doodle's disability, but they press on, because the narrator's pride will not allow him to stop. Finally Doodle stands up on his own, and eventually he can take a few steps by himself. They reveal their success to everyone on Doodle's sixth birthday, and everyone is happy with the narrator for teaching him; the narrator cries, though, because he knows he did it more for himself than for Doodle.
Eventually the narrator believes that he can teach Doodle to do anything, so he decides to teach him to run, swim, climb trees, and fight, so that the following year he can start school on the same level as all the other children. They do not get much practice in that winter, but when spring comes they begin to work hard. However, that summer is terrible, and the family loses a lot of crops. School comes up fast, so the brothers redouble their efforts so that Doodle will be prepared. Doodle, however, is being pushed beyond his limits.
A storm is on the horizon one day, and while they sit and eat lunch they spot a huge red bird in a nearby tree. When they go outside it flies down to the ground and dies at their feet, apparently hurt and exhausted from being thrown off course by the storm. Doodle is especially sympathetic, and gives the bird a proper burial.
After they finish eating the brothers head down to the creek to practice rowing. Doodle is clearly not up for this, but the narrator pushes him anyway. The storm approaches while they row, and when they get back to the bank Doodle is so exhausted and frightened that he collapses into the sand. The narrator helps him up and they attempt to race the storm back home, but Doodle's body is done in and he collapses again. He calls out for the narrator not to leave him, but the narrator has one of his strokes of maliciousness and runs ahead.
The narrator finds his senses and waits for Doodle to catch up, but he never does. He retraces his steps, only to find his little brother lying in the sand, covered in blood from his mouth, dead just like the scarlet ibis. The narrator is devastated, and lies protectively over Doodle's body, crying, to shelter it from the rain.