Radiance Descending (Hardcover, Turtleback School & Library ed.)

Paul is so angry that his younger brother, Jacob, has Down's syndrome that he's embarrassed to be near him. Paul can't see that Jacob idolizes him. In Paul's view, Jacob gets all their family's attention, and it's hard for Paul to love someone so clumsy and strange looking. Yet people outside the family welcome Jacob and embrace his kindness. Paul thinks these people are simply pretending to be nice to his brother. Then, through a series of surprising events, Paul begins to wonder whether Jacob is indeed a person worth loving.