Why is the narrator sometimes angry and disappointed in Doodle in "The Scarlet Ibis"?

Doodle was born when the narrator, Brother, was six years old.  When Doodle came into the world, he was physically disabled, and the family was concerned if he was mentally disabled as well.  Brother describes him as “all head, with a tiny body that was red and shriveled like an old man’s.”  Brother even calls him a “disappointment.”  Once the family realizes that Doodle is not mentally disabled, Brother finds new interest in Doodle and...

Doodle was born when the narrator, Brother, was six years old.  When Doodle came into the world, he was physically disabled, and the family was concerned if he was mentally disabled as well.  Brother describes him as “all head, with a tiny body that was red and shriveled like an old man’s.”  Brother even calls him a “disappointment.”  Once the family realizes that Doodle is not mentally disabled, Brother finds new interest in Doodle and plans to teach him to run, jump, climb a rope, and swim in Old Woman Swamp.  Brother is embarrassed by Doodle’s physical disabilities and wants to make him as normal as possible.  To please Brother, Doodle pushes beyond his physical capabilities and does learn to walk.  At the end of the story, Doodle dies, exhausted by his efforts to run and catch up with Brother in a storm. 

Brother’s pride caused Doodle’s death; he was dissatisfied and embarrassed by Doodle’s physical flaws, and left him behind.