When a child dies, guilt and blame almost always enter the scene. "The Scarlet Ibis" explores that phenomenon. Brother is racked with guilt over the death of his little brother Doodle when Doodle was six and Brother about thirteen. Though Brother's actions are the direct link to Doodle's death, there are a variety of other factors that come in to play; Doodle's heart condition, the lack of knowledge in the early 1900s about heart disease, and perhaps even a lack of supervision and perception on the part of the boys' parents are things to consider when analyzing this story. The story also addresses, though subtly, the destructive impact guilt can have. The story asks how a person who feels responsible for a loved one's death can acknowledge that responsibility, but still enjoy life, and be happy.
Brother is a victim in "The Scarlet Ibis" because he's a child allowed to take on adult responsibilities; when tragedy strikes he's traumatized by the resulting guilt.
Brother's feelings of guilt could have a positive effect on his life by making him more careful of the people he's around.