The narrator is not happy to have a brother who couldn't do thing a normal child did. When Doodle was born they expected him to die so they bought a casket, but Doodle survived and soon was able to crawl and walk thanks to his brother.
The narrator was not happy that he had to take his little brother every where he goes and because he can't walk he has to constantly has to watch him.
Doodles brother was embarrassed because Doodle was 5 years and couldn't walk so the narrator took it upon himself to teach Doodle how to walk. Doodle kept trying to give up bu the narrator encouraged him to keep trying and he did it he walked.
The narrators Family learns that Doodle can walk and the are very happy, but the narrator is very upset because he feels that something will happen to Doodle and it will be his falt.
I can Walk!
Doodle and his brother started running to escape the thunder storm and Doodle couldn't keep up with his brother and ended up dying because he over exerted himself and his heart stopped.
Doodles brother is feeling remorse over his death because he pushed him too much when the doctors to his family not to. So the narrator feels responsible for his brothers death.