What is strange about Amir's vision of himself and his father meeting in the same way as Rostam and Sohrab?

Hassan's favorite book by far was the Shahnamah, the tenth-century epic of ancient Persian heroes. He liked all of the chapters, the shahs of old, Feridoun, Zal, and Rudabeh. But his favorite story, and mine, was "Rostam and Sohrab," the tale of the great warrior Rostam and his fleet-footed horse, Rakhsh. Rostam mortally wounds his valiant nemesis, Sohrab, in battle, only to discover that Sohrab is his long-lost son. Although you can read the story of "Rostam and Sohrab" as an allegory for Baba and Amir's relationship, we think the most obvious parallel is to Amir and Hassan. Amir doesn't kill Hassan directly, but he does bring about Hassan's exile from Baba's household. This exile eventually places Hassan in a situation where he is killed. Amir, to some extent, takes the blame for Hassan's death. Like Rostam, Amir figures out much too late who fathered Hassan. We think you could very easily substitute "brothers" for "sons" in the final sentence: "After all, don't we all in our secret hearts harbor a desire to kill our brothers?" ("Cain and Abel" seems just as appropriate as "Rostam and Sohrab.")