A/b/o DesMal?? (Desmond x malik)
Okay, so this could be set in a Modern Day AU or Desmond gets booted into the Third Crusades but here are some of the things that would happen:
Desmond would obviously be mistaken for Altaïr unless they get closer and sniff him. That’s why, as weird as it sounds, anytime Desmond is mistaken for Altaïr, he just sighs and says “Come closer and sniff me”. There’s a lot of different reaction to that one.
We can go for the route of Altaïr and Desmond are twins or cousins. Or we can go for the route of they’re not related and this is a quirk of fates or some shit. (Even in the case of Desmond getting booted into the Third Crusades, Desmond would have to pick one of those choices because saying “he’s my ancestor and I’m a time traveler.” isn’t really an option)
Malik is one of the few people who can differentiate the two without having to sniff (Desmond) or be glared at (Altaïr). He doesn’t say it but that’s because he can always smell Desmond’s scent even before he should be close enough for Malik to see him.
Desmond smells like freshly baked sweet bread to Malik.
Malik smells like cotton candy to Desmond. He can’t really explain it but it’s not that Malik smells like real cotton candy but that’s the image that pops into Desmond’s mind when he catches Malik’s scent.
Malik isn’t an idiot, he knows this could only mean that he and Desmond were highly compatible and Desmond hasn’t been that subtle in checking if Malik was interested in him. Definitely not subtle enough since Altaïr could see it and would always have that pinched look on his face before leaving the room Desmond and Malik were in without even saying goodbye (which is rude).
He is also very much interested in Desmond, it’s just… he didn’t expect to actually find a mate himself. He had been uninterested for as long as he could remember and he had accepted that his younger brother would be the one to carry the Al-Sayf line (Although, really, he wished Kadar wasn’t so smitten by Altaïr of all alphas) so it takes a bit for him to accept that, yes, he and Desmond are compatible and, yes, the more he thought about it, the more he liked the idea of being mates with Desmond.
Fated mates sorta exist in this idea in the sense that it’s a legend and there have not been any real records of it. The general consensus is that it’s more of the case of ‘you are fated mates because you both fell in love with one another and your scents are compatible’
Desmond would be moping during that time Malik is sorting his feelings since he’d take Malik’s silence as rejection and Altaïr has to be the one to suffer smelling the sadness from Desmond.
So when Malik started courting Desmond (all proper and traditional, complete with a mated chaperone in the form of Rauf (if this is during the Third Crusades) or maybe someone like Bayek or Ezio (if this is a modern day AU)), his biggest wall is now the fact that Desmond believed he’s courting him because Malik noticed him ‘moping’ and felt bad so this is… a pity-courting thing.
Malik should be offended but he knows he fucked up by being silent and it was such a dumb move that an idiot like Altaïr would have done (cue Altaïr’s offended face in the background as he snarks that he would have gone at full speed if it had been him, shut up Altaïr that's not any better!)
So now Malik has to show Desmond that he’s being sincere and that he wants a future with Desmond. Maybe even have a scene where it all comes to head and Malik blurts out how many kids he wants and Kadar is in the background just going “back it, brother! Too far!!!” but, jokes on them, Desmond is into that XD
So… I’ve been quite vague on whether they’re alphas/betas/omegas. The main reason is because I think this could work with any kind of combination you want and, honestly, Desmond and Malik could be alphas, betas or omegas if you want. I will say that I made Altaïr an alpha because part of the setup is that Altaïr is going to make Malik’s life a bit harder because he kinda adopted Desmond as his sorta sibling (if they’re not actual siblings in the setup)/child and the shit Malik did definitely deserves some sort of metaphorical punching. Kadar can be a/b/o, your choice. Also, just because Malik is the one courting doesn’t mean he can’t bottom if you want. That’s also the reason why their a/b/o status is vague.