Doodle is able to move himself around starting at the age of two, but only while lying on his stomach. The doctor thought the strain involved in this movement would kill him because of his weak heart, but it doesn't. In this manner, Doodle learns to crawl for the first time, and the family begins to bring him out into the living room in front of the fireplace to crawl around rather than just lie in the bedroom all the time. For the first time, according to the narrator, Doodle becomes one of them.
The family called him William Armstrong while he could do nothing except lie in bed, but now that he has begun to crawl around and develop a personality of his own, they decide they have to change the name. The name "Doodle" comes from his unique movement; Doodle crawls backwards rather than forwards, and this makes him look like a doodlebug, the larva of a type of insect.
The narrator's mother and father think this name is better than William Armstrong, too; everyone thinks so except for Aunt Nicey, who thinks that a baby born in a caul like Doodle deserves a more respectful name since he might turn out to be a saint. The narrator says that changing Doodle's name was probably the nicest thing he ever did for him, since "nobody expects much from someone called Doodle."
Doodle doesn't show any signs of walking anytime soon, but he does talk a lot, so much so that the family even stops listening to what he says. Doodle’s father builds him a go-cart, and it's the narrator's job to pull Doodle around and take him along whenever he goes somewhere. Even though he is showing improvement, Doodle is still a burden in many ways. There are a lot of things they cannot do around him, but the narrator ignores these when he leaves the house with Doodle. He would do things like run too fast with his cart and tip it over in the hopes that Doodle would be discouraged from coming outside with him again.
Eventually, though, the narrator accepts that Doodle is his brother and he will not get rid of him anytime soon, so he decides to share with him the Old Woman Swamp, which he believes is truly beautiful. Doodle is mesmerized, so much so that he starts to cry and proclaims it "So pretty, pretty, pretty." After that day, the narrator takes Doodle to the swamp very often to gather flowers and weave them into necklaces and crowns. They wear them for a while, and then drop them in the stream to watch them float away.
The narrator admits that many times he was cruel to Doodle. One time he takes him to the barn and showed him the casket the family had had made for him, because they believed he was going to die. He forces Doodle to touch it and threatens to leave him in the spooky barn himself if he doesn't. Doodle screams and will not move after he touches it, so the narrator carries him out of the barn as he screams, "Don't leave me. Don't leave me."
Section 2 is very much devoted to characterization. Readers learn a lot directly about Doodle through the narrator's descriptions of him. Once again Doodle shatters expectations others have for him by learning to crawl, when the doctor thought even the strain of movement would cause his death. We learn that he loves to talk, and he talks so much that people stop listening to him. Doodle's talkative nature is very important, because for a long time it was presumed that this character was going to die, which means he would be silenced without a voice at all. This sits in start contrast with what truly happened; now Doodle is very much alive, and his voice is the loudest of all.
Doodle's appreciation for the world full of beauty says a lot about his character, too. It is striking that he can grasp the power of this beauty even more than anyone else, since he nearly did not live to see it. Doodle displays to readers a sense of awe and admiration about the world that many who take their surroundings for granted do not have. The beauty of the Old Woman Swamp also represents a forged bond between the brothers, who originally did not get along very well. Old Woman Swamp is their version of an ideal world, where, free of burden, they can be the kind of brothers that the narrator wants them to be. The narrator and Doodle can connect over their love of the beauty in nature, and the narrator is willing to bring Doodle along with him when he visits the swamp because it allows some release of responsibility.
Indirectly, though, readers learn a lot about the narrator through the way he describes Doodle and their interactions. The narrator develops a grudging acceptance of his little brother, but still harbors some animosity towards him for coming in so abruptly and shaking up his life. Though they have formed a bond, it is still clear that the narrator wishes Doodle were able-bodied and normal. Moments such as the scene with the casket prove this.
The casket is a symbol for Doodle's death, and the easier life that the narrator would have had had Doodle not survived. The narrator brings Doodle to see his casket as a punishment for being alive and being a burden. Doodle loves life, so this is a traumatizing moment for him. He responds with a plea for the narrator not to leave him alone with the casket; in other words, he does not want the narrator to wish him dead or reject him.
This section further elaborates on the main conflict in this story. The conflict is actually something that many would see as a good thing: Doodle is alive. Doodle did not die when everyone said he was going to. This creates a new responsibility in the lives of all those connected to Doodle, particularly the narrator. The narrator has many perceptions about what a brother should be, but instead he got Doodle, a disabled, clingy boy who follows him anywhere. The narrator must attempt to resolve the battle between his expectations and his reality, and this is the major conflict in "The Scarlet Ibis."
Though she is a minor character, Aunt Nicey serves as the voice of reason and warning throughout much of the story. She constantly reminds the family to treat Doodle with respect, and she believes right from the start that he will be more than everyone thinks he will be. Her opinion of this boy is juxtaposed with the narrator's opinion; the narrator believes that Doodle's disabilities have made him the opposite of an ideal brother, while Aunt Nicey believes they make him sacred and special.