How does the narator of "Sonny’s Blue's" change and what brings about his change?

The way the story starts and the narrator's clear feelings
of shame and anger at his brother's involvement in drugs and jazz music present us with
a massive conflict that clearly shows no sign of being resolved. The narrator himself
wonders whether the seven years that separate himself and his younger brother can ever
be bridged. However, the key moment of transition comes when the narrator learns from
his mother that his father had a brother who died as a result of a drink-driving related
incident perpetrated by white men. The mother tells the narrator this story to try and
make him see how important brothers are to each other in supporting and helping each
other through life, especially as Sonny is struggling. This causes the narrator to feel
guilt as he reflects that he has not been there for his younger brother in his
difficulties. He also however recalls with anger his disappointment that Sonny chose to
follow jazz music over classical music, a choice that was "beneath him" from the
narrator's perspective. It is clear that the two brothers follow very different
lives.

The next key transitional moment comes when both the
narrator and Sonny witness a revival scene. The brothers talk and it is clear that the
narrator is genuinely trying to understand his younger brother and his perspective. When
Sonny shares with his brother how the revival meeting made him think of how heroin gave
him the feeling of being in control, the narrator discerns that Sonny is really
referring to a much greater issue: the way that, for Sonny, heroin was a preventitive
measure to keep Sonny from "drowing in" the sorrows of humanity. He continues to expand
on this, saying that for us to learn from suffering we have to be able to "own" it. For
Sonny, the two things that helps him "own" this suffering is jazz music and
heroin.

The change in the narrator is finally confirmed at
the end of the story, when he agrees to accompany his brother to a jazz club and hear
him play. As he hears Sonny take the lead in a jazz song, he finally realises how music
can be a vehicle can help people to express and learn who they are and how it can keep
them from drowing in the sorrows of humanity, as Sonny has obviously discovered. He has
finally experienced and understood his younger brother's
perspective.