I love Altair and Darim.
We don’t know much about Darim and his relationship with his father. But it’s not too difficult to imagine that it must have been very hard for Darim to understand and love him. Altair didn’t actually have a pleasant character and his personality became even worse after Sef and Maria’s death. I think it’s very realistic that Darim was driven away from Altair for so many years, due to his depression and his obsession with the Apple. Still, in this scene he says “Everything that is good in me, began with you, father”. And Altair is clearly moved, in his own controlled way. For me this is a small show of that kind of love and respect between a father and his son, that cannot be affected by differences and misunderstandings.