Who was Rahim in the book The Kite Runner?

Rahim Khan is a well educated friend of Amir’s father. He is the first adult Amir considers a friend. He readily reads Amir’s stories and buys Amir a notebook for his birthday, an encouragement for Amir to follow his talent on this front. Rahim Khan is the person to reveal that Amir and Hassan are half-brothers when he tells Amir about Hassan’s son. He is living in captivity in Afghanistan.