What is Harlan asking when he says “What about you?”

Harlan is asking is his son still felt the same way about his "father" now that he had seens and experienced so many things. Just before, Hiram asked his father if he stopped loving his father.... when Harlan turns the question back on him.... "what about you?", Hiram can't answer him because he isn't sure, not knowing that he wan't talking about his grandfather at all.... he was talking about their relationship.