The narrator says it was the kindest thing he did for his brother because no one expected much from him, but it was kind because he was showing an interest in him and giving him life.
The narrator renames his little brother with a playful name rather than the serious name that he was born with. When Doodle is born, he looks so sickly that everyone is sure he is going to die. He is given a coffin before he is given a name.
Daddy had the carpenter build a little coffin, and when he was three months old, Mama and Daddy named him William Armstrong. Such a name sounds good only on a tombstone.
The family is depressed by the little boy’s appearance and general lack of robust health, but his brother refuses to give up on him. He decides to make him crawl, and gives him the name Doodle because of the funny way he moves.
The name Doodle came from the fact that the boy crawled funny, crawling in the reverse.
This made him look like a doodlebug, so I began calling him 'Doodle.' Renaming my brother was probably the kindest thing I ever did for him, because nobody expects much from someone called Doodle.
The brother generally seems to be the one who expects the most from Doodle. He expects him to crawl, and later to walk and be active more like a normal kid. He gets too frustrated when his brother can’t do something, so he expects him to be able to do what a brother would normally be able to do. He may have a silly-sounding name, but at least he is alive and getting stronger. Unfortunately, he might push his little brother a little too far, and he pays the price for that.
This very sad tale ends with Doodle's death, showing that his name foreshadowed his doom after all. The brother, who was never really able to handle the disappointment of having a defective little brother, pushed Doodle too hard and then abandoned him when he needed him most. He did love and care about his brother, but he was just a child too, and not ready for the huge responsibility.