What flaws does the narrator have in "The Scarlet Ibis"?

Central to this tragic tale is the inability of the elder
brother, the narrator of this story, to allow his brother to be who he is. He is clearly
driven to train and teach Doodle how to do physical activities that are mostly beyond
him, and yet this compulsion is not borne out of a sense of love or compassion for his
pitiful younger brother. Rather, the text makes clear that it is a sense of
embarrassment and pride that leads the narrator to invest so much time with Doodle and
try to "improve" him. Note that the text informs us that the narrator teaches Doodle to
walk because he was "embarrassed" to have a five-year-old younger brother who can't
walk. This leads to a moment of tragic realisation when Doodle displays his talent to
their parents, and the narrator realises what motivated him to work with Doodle so
hard:

They did
not know that I did it for myself; that pride, whose slave I was, spoke to me louder
than all their voices; and that Doodle walked only because I was ashamed of having a
crippled brother.

Thus the
narrator here himself identifies his biggest flaw: pride, who, as he says, had him in
slavery. It is this same pride that leads us to the story's tragic conclusion. When the
narrator and Doodle are forced to admit failure, note what the narrator
says:

We never
spoke (what are the words that can solder cracked pride?), but I knew he was watching
me, watching for a sign of
mercy.

Key to identify is the
metaphor comparing the "cracked pride" of the narrator to an object that cannot be
soldered together again or repaired. Doodle is described as desperately watching for a
"sign of mercy," but this is something that, because of his slavery to pride, he is able
to fulfil.

In a sense, then, Doodle meets his sad and
tragic end precisely because of the flaw of his brother, who is unable to accept Doodle
for who he is, with his limitations, and thus is driven by his pride to try and
transform him into something that Doodle could never be.