What is the relationship between Sonny and his brother and how does it change?

The basic conflict of the story, which is the older
brother’s story, is the narrator’s inability to understand and respect the life of the
younger brother he so clearly loves. Baldwin carefully establishes the brothers as
opposites. The narrator is a cautious, respectable family man. He teaches math and is
proud of his professional standing. Living in a Harlem housing project, he consciously
protects himself from the dangers that surround him. Notice how intensely he appears to
dislike Sonny’s friend, the drug addict, when he encounters him in the school courtyard
at the beginning of the story. However, the narrator is also compassionate, and it is
important to see, in the same episode, how quickly he recognizes and responds to the
addict’s battered humanity. That gesture prefigures his reconciliation with his brother.
Sonny, by contrast, is a romantic artist who is not afraid of taking risks to pursue the
things he desires. His passion for music makes him impatient with everything else. He
drops out of school. In his brother’s view he is “wild” but not “hard or evil or
disrespectful.” At the end, the older brother comes to love his brother by offering him
a drink, not because he is insensitive to the aspects of addiction, but his love for his
brother trumps all other emotions.