Why does Amir really invite Hassan to the hill before he throws pomegranates at Hassan?

one day, he asked Hassan to climb the hill with him to hear a new story. Hassan joined him eagerly. After they picked pomegranates, Amir asked Hassan what he would do if he threw a pomegranate at him. When Hassan said nothing, he threw the fruit at him and demanded that Hassan throw one back. As Hassan refused to fight back, Amir threw countless pomegranates at him until he was stained in blood-red juice. Finally, Hassan smashed a pomegranate against his own forehead and asked, "Are you satisfied? Do you feel better?" before leaving. Amir is looking for some kind of penance, some pain Hassan might inflict upon Amir to make him feel better.