how is ali and hassans birthday gift significant chapter 9

Both gifts bring Amir shame. The morning after his birthday party, Amir opened his presents joylessly. To him, each gift was tainted with Hassan's shed blood. He knew Baba never would have thrown him such an extravagant party if he had not won the tournament, and to him the victory was inseparable from Hassan's rape. Baba himself gave Amir a coveted Stingray bicycle and a fancy wristwatch, but they too felt like "blood money." The only gift Amir could stand to enjoy was the notebook from Rahim Khan. When Amir took his new bike for a ride, Ali and Hassan were in the yard cleaning up the mess from the party. Ali stopped Amir to give him a present from himself and Hassan, a new copy of the Shahnamah, the book from which he had so often read to Hassan. When he got home, Amir buried the book at the bottom of his pile of presents so it would not torment him with guilt. Then he began scheming how to get rid of Hassan. Before he went to bed, he asked Baba if he had seen his new wristwatch.