Even though the narrator tells us he had Fantasies of killing his brother, what is the first indication in the story that he really loves him?

The narrator describes the first time his brother smiles at him.

My head poked between the iron posts of the foot of the bed, he looked straight at me and grinned. I skipped through the rooms, down the echoing halls, shouting, "Mama, he smiled. he's all there! He's all there!" and he was.