Without it Altair is weak, aggressive, he costantly seeks approval and clings to everyone within his reach (Al Mualim, a father figure then Adha, idealized object of fatuous affection).
Caring and support that he gets from Malik and Maria help him become a true leader and regain inner balance. They mean a world to him. He needs them desperatly and their death drives him into deep depression.
Think for a moment about hours or even days that Altair spent in the library alone, waiting, no longer motivated by his duty, determined to die.
This was the message conveyed through the Masyaf Keys. Ezio understood it after watching Altair’s memories. He finally decided to lay down his sword and declare his feelings to Sofia.
Cazzo! Nothing but snow for yards and yards! Templars could be hiding anywhere! Damn this Pennsylvania countryside!