Furthermore, when his little brother starts playing the piano and gradually produces better music the narrator and all of the people in the club are captivated, making it obvious that Sonny believed that his passion could surpass heroin in putting his suffering behind. The devastating news that the narrator's uncle was murdered has a somewhat beneficial effect on the narrator, given that he takes on the role of caring for himself and the rest of the family. Suffering and the diverse methods through which it can be subdued is the main theme of the short story. The suffering produced by the fact that society rejects him influences Sonny's passion for playing the piano. The drug bust makes the narrator aware that he does not know Sonny and that his brother is completely alone, inducing a feeling of remorse. Later on, with the narrator's daughter, Gracie, dying...

Gracie's death is the actual reason for which the two brothers are reunited, since the suffering both of them had come across during their lives made them aware that family was essential in getting over harsh times.
Music saves Sonny from becoming a total failure, since it is the reason for his enlightenment, his ticket out of Harlem, and thus out of heroin addiction. Considering that music and heroin are the two methods Sonny uses to escape suffering, it is only natural for one of them to better the other at a particular moment in the man's life. The fact that music turns out to beat heroin as Sonny's main tool against pain can virtually be considered his epiphany.

Works cited:

Baldwin, James. (1965). Going to Meet the Man -- "Sonny's Blues." Dial Press.