Why did Hassan name his son after one of the characters in The Kite Runner?

When Amir and Hassan, the main characters of Khaled
Hosseini's The Kite Runner, were young boys, they often dreamed of
being like the heroes of one of their favorite stories, the
Shahnammah. The main characters of that story were Rostan and
Sohrab, and Hassan never forgot the good times spent with his wealthy friend on the hill
under the pomegranate tree. It was an important time for him, and when it came time to
name his son, he named him Sohrab. In a letter to his long absent friend that is only
delivered after his death, Hassan tells Amir that he and his son still return to the
same tree to read the stories from the
Shahnammah.