Narrator and point of view

The novel The Kite Runner by Khaled Hosseini is narrated in the first person by Amir, the main character. The narrator focuses on events that took place decades before, from the time he was twelve years old to the present day when he is an adult. The events are told retrospectively from Amir’s perspective except for two chapters when the narrator changes. 

The events are told by an adult narrator, who pinpoints the exact moment when his life took a different course: 

I became what I am today at the age of twelve, on a frigid overcast day in the winter of 1975. I remember the precise moment, crouching behind a crumbling mud wall, peeking into the alley near the frozen creek. (Chapter 1, 0%)

The adult narrator is more knowledgeable than his younger self, so it is easier for him to comment on his faulty behavior. For example, when he thinks about the moment he chose not to intervene and save Hassan from Assef, the adult narrator evaluates his behavior in an analytical yet detached wa...