what is significant about the pomegranates growing on the hill?

Hassan's name means "handsome," which is ironic because people make fun of Hassan's appearance; in another sense, it is perfectly fitting because Hassan's inner beauty and purity of spirit is what makes him such a respectable and lovable character. When Amir throws the pomegranates at Hassan, he is begging for Hassan to absolve him by hurting him. Instead, his torture continues; he sees juice running down Hassan's shirt like blood, reminding him that Hassan's blood is on his hands. In the end it is Assef who "heals" Amir by hurting him.