#Altaïr of course possessed him but he really thought Desmond decided that was the end of his life right there and that

[theconfusedartist]

ok, so (au headcanon time, this is permutation 1 but the scars bit is pretty consistent through the other permutations as well)

I feel like, since Desmond and Altaïr are living their lives concurrently, they both wanted to kill each others respective parental figures (not Umar he's cool)

Desmond wants to kill Al Mualim due to his treatment of Altaïr after Umar's death, how he taught him to be as a tool only for his bidding, multiple times Desmond has tried to kill the man but Altaïr stops him. Not because he loves Al Mualim but because of how everyone treated him after he told Abbas about his father. Rather than any of the other assassins corroborating the facts, they all kept silent and let Al Mualim neither confirm or deny what happened to Abbas' father, which ended up destroying the friendship he had to the person he was closest to. And after that they were both left in solitary confinement for a month, which would be hard in anyone, let alone a pair of grieving 11 year old children. Desmond realized exactly was Al Mualim was doing, and while Altaïr doesn't go against him until the AC1 events, he knows he has someone who will never leave or abandon him in his corner and would even kill Al Mualim if only he asked

On the other hand, any thoughts of vengeance were outright beaten out of Desmond, and the turning point was when he got his scar at a 11 (yes, they both got their scars at 11, it's all to do with the concurrent thing). William, who had been in a terrible mood, woke Desmond up in the middle of the night and demanded that he come down to the training ring behind their house in the woods for practice. William had two real hidden blades, and Desmond (who usually doesn't get a weapon) had a hidden blade made of wood that he'd crafted a few days before. To Desmond, this entire thing was nothing new. He'd go back to bed after tending to his injuries, and William was tired from beating down on him. That night was different. His mood was far more foul than he had anticipated, and William cut his blade from the side of his nostril all the way down to his chin. William takes him back to the house, to tend to his wounds, but he makes it very clear that what had happened "was an accident". Altaïr is having none of this and attempts to strangle him, causing William to flee as he starts choking.

Desmond had been wary of Al Mualim and distrustful, but it's not until Altaïr gets his scar that he's actively trying to kill him whenever he tries giving Altaïr private lessons. Altaïr got his scar from Abbas, but Al Mualim had been watching from afar and didn't step in until he saw Abbas was going for the kill. No one stepped into help until "oh, that's a bit too far," and even then, rather than coming clean to Abbas and telling him what happened, Al Mualim punishes them both. While Al Mualim can claim he wasn't the one who gave Altaïr the scar, the responsibility also falls on him because he saw what was happening and let it play out, before using the advantage to his situation.

William doesn't bother hiding what he's doing because no one ever comments when Desmond gets bruised up or hurt, and they'll either shrug it off as "an accident" or just "a mishap at training" if he walks around with a black eye. William knows he can get away with whatever he wants, so he just calls it an accident, and it doesn't matter what he does or he sees it, they will always corroborate the story he puts out.

The difference between Desmond and Altaïr is that Altaïr doesn't want to leave the life of being an assassin because it's all that he knows, and believes that he can still find purpose in the life his father once lived. Desmond wants to leave the assassins *because* its all he's ever known. Altaïr, once he reaches a certain rank, can still leave Masyaf and travel, he won't always be under Al Mualim's eyes, but if he stays an assassin Desmond will never be able to escape William and the people who refuse to stand up to him. To Desmond, being an assassin is all he's ever known and he wants to know more than that.

The parallels...