Since Sonny's brother, the narrator, has internalized many of his "blues," or sufferings, they are subtly revealed and the reader feels sympathy for him.

• When he first reads of Sonny's arrest, feelings that have been suppressed re-emerge and "stare at" him in his "own face, trapped in the darkness which roared outside" as he stands in the subway:

A great block of ice got settled in my belly and kept melting there slowly all day long....It was a special kind of ice....when I was remembering some specific thing Sonny had once said or done.

• The brother has great difficulty thinking of Sonny going to jail in this darkness of his life, much like the darkness of the lives of the boys he teaches algebra. His dread of the future is poignant.
• After his daughter Gracie dies, the narrator writes to Sonny in an attempt to reach out to him now that he understands suffering.
• After he picks Sonny up and in the taxi they drive through "the vivid, killing streets of our childhood." They pass houses much like the houses of their youth and see boys just like the boys they have been, some of whom will get out, but will "leave something of themselves behind."
• As the narrator brings Sonny into his house, he has the "icy dread" again and feels that he 

...was simply bringing him back into the danger he had almost died trying to escape.

• In the flashback about the brother's attempts to care for Sonny, the reader's sympathies are evoked by his conflicts with Sonny, After he returns from being in the military, Sonny tells his brother he wants to become a musician. The narrator assumes Sonny wants to be a classical musician, but he desires to be a jazz player. This announcement puzzles the narrator who has subsumed some values of white society into which he attempts to integrate,

I sensed myself in the presence of something I really didn't know how to handle, didn't understand."

• Years later, after Sonny listens to the street preacher, he opens up to his brother, telling him how much the woman singer must have suffered to have sung as she did. The narrator responds, but really desires to say more, but is incapable of reaching out to Sonny.  It is, perhaps, at this point that the narrator senses that Sonny is his darker side, certainly a touching point.
• Finally, when the narrator accompanies his brother to the nightclub, and, at last, he understands why Sonny must play music, there is an epiphany in the brother that arouses feelings of sympathy in the reader who realizes the beautiful communion of the two souls as the narrator observes,

What is evoked in [the man who creates music] ....is of another order....his triumph, when he triumphs, is ours....apprehension began to beat the air.

• By listening to Sonny, the narrator apprehends that music is solace for the suffering soul, and the reader rejoices that he has learned to understand that Sonny is "playing for his life."