What is textual evidence for the brother in "The Scarlet Ibis"?

Brother is a somewhat selfish but also mostly empathetic adolescent.

The narrator in this story never tells us his name.  This is a way of distancing himself from the guilt that he feels as he tells the story.  Although he did not mean to, he is responsible for his brother’s death.  It is something tragic that happened and he will never get over it.

Brother often behaves harshly and even cruelly toward his younger sibling, Doodle.  He wanted a younger brother so badly that getting one that was less than able is hard for him.

I wanted more than anything else someone to race to Horsehead Landing, someone to box with, and someone to perch with in the top fork of the great pine behind the barn, where across the fields and swamps you could see the sea. I wanted a brother.

Doodle is not capable of running and jumping, or being a playmate in the sense that most brothers can be.  He is too weak and can’t even walk until his brother teaches him.  The narrator does not teach Doodle how to walk just out of the kindness of his heart.  He is embarrassed by having a brother who is five years old and still can’t walk.

Doodle’s brother does his best to make his little brother into what he feels that a brother should be.  He forces him to grow and get stronger.  However, he is often very mean to Doodle.  The worst example of this is when he causes his brother’s death by pushing him too hard.  Although he was angry at Doodle for not keeping up, he is horrified and wracked with guilt when he realizes what he has done.

I began to weep, and the tear-blurred vision in red before me looked very familiar. "Doodle!" I screamed above the pounding storm and threw my body to the earth above his. For a long time, it seemed forever, I lay there crying, sheltering my fallen scarlet ibis from the heresy of rain.

Even though he did not approve of his brother’s weakness, he did not want his little brother to die.  He still loved him despite his flaws, and in his own way was just trying to keep pushing him until he became normal.  He was just a kid himself, and not aware of where to draw the line.  He paid for his mistake with his brother’s life, and would never forgive himself.