What does it mean that, in the picture of Baba and Rahim Khan, Amir is holding onto Rahim Khan?

Amir tells of a picture of his father holding him as a baby "looking tired and grim" but although Amir's Baba is the one holding him, Amir is holding on to Rahim Khan's ( his father's best friend) finger. This shows that the distancing between father and son began at birth.

I think Amir really didn't have a father figure in Baba. Amir was much more comfertable with Rahim Khan in a father sort of roll.