Why Did Hassan Get Rapped?

Hassan was raped and Amir just watched and then walked away. Amir didn't want to help Hassan or stop the people when he was in the alley. Amir didn't help when he got raped because Amir wanted the blue kite to gain his favor with his father. Amir wanted him to be raped also to make Hassan to be weak to Baba.

Why did Amir have Hassan raped?

Most notably, Amir allowed Hassan to be raped in part because he thought bringing home the kite would win him Baba's love, relieving him of his guilt over his mother's death and making him happy.

What did Assef do to Hassan in the alley?

What happened to Hassan in the alley? When Hassan refuses to hand over the kite he ran for Amir, Assef pins Hassan to the ground and rapes him.