Sonny certainly is rebellious due to his checkered past and his time in prison. His brother has also rebelled, but in different ways. Sonny has his own insecurities about being able to function in society due to this checkered past, and his music is the only way he feels he "fits in." It is his escape and his solace. His brother finally realizes this at the end of the story. His epiphany is that he finally realizes that he finally understands Sonny's connection to and passion for his music.