It is John Gardner's novel "Grendel" from 1971 that initiated the trend of telling a story from a monster's point of view. The story is essentially the epic poem Beowulf spoken trough the eyes of Grendel
Amir feels unbearable shame for mistreating Hassan. Amir feels as though Assef has been diminished by his own darkness. They were both comparable characters who just chose opposite paths, which is reminiscent of the hero/villain narrative in the movies they loved to watch. To demonstrate how Amir is developing and becoming more self-aware, Hosseini shares this dream.