Well, so far in this book, this is a story of two boys who grew up together...ok, i give up. i cant explain it without a diagram, so here, i made one :D
This describes how they're related [in a sense]
Agha grew up with Ali like brothers, but ali was also his servant. they were practically best friends [[or as emily says it: biffles <33]]
They both had a son, and they hoped that the two sons would be best friends too. Amir thought that way, but hassan just treated him like a best friend only wen it was necessary. You see, there was like a social division between them. Ali and his son were hazaras, which were hated by pretty much everybody. So, whenever Amir and hassan were alone, they would play, but when Amir was with other people, he would ignore Hassan.
One day, when Hassan and amir were kite flying [[which was amir's most important day, because he would finally be recognized by his father]], amir won first place! Hassan ran, chasing that kite for Amir, and said "For you a thousand times over!" Well, it took a while, and when Amir went searching for him, he found that Hassan was being picked on and all he had to do was hand in the kite, and he wouldnt get hurt. He wouldnt let go. He promised Amir that he would get the kite. Then, Amir turned away in cowardice. Hassan was raped.