I am curious, why is Draxum so protective and secretive over his mask and anyone seeing his face in your MI AU? is his mask like a safe object since he is written to be neurodivergent?
There's a couple of different reasons, and one of them definitely is that is a safety/comfort object for him. Backstory-wise, he's had it for centuries, making it one of the possessions he's held onto the longest. Given how much he used to travel, it might be the only one he's managed to hang onto. It was also probably a gift from someone he cared about, and likely the only thing he has to remind him of them.
Also, the sensory blocking spell he cast for Mikey in ch 17? Draxum uses that kind of spell himself, usually casting more than one and using his mask as a sort of focal point. (Also he can toggle the spells on and off, so it's kinda like constantly carrying noise-canceling headphones around for him? But for other senses too? I'm still fleshing out the mechanics lol)
But another reason for the mask? Well, he's masking, literally as well as figuratively. He's hiding his 'true' self (one that, as shown in season 2, is more expressive and outright emotional). He doesn't feel comfortable revealing his actual face or even having it acknowledged that he's hiding a pretty important part of himself, but also? He wears the mask so much that he thinks of it as his actual face. His self-perception is so rooted in hiding a part of himself that he no longer thinks of it as hidden--he doesn't think about it at all.
This is more or less why Leo hasn't seen Draxum's actual face yet, even though he's been waking Draxum up at ridiculous hours of the night for a while now. Draxum wakes up and puts the mask on like a pair of glasses, and once he has it on he essentially forgets he's wearing it. Yes, part of it is that on some level Draxum doesn't like or want the vulnerability of showing Leo his face, but he's so used to wearing it that it feels more like him than his real face does.
TLDR: it's a symbol of Draxum's neurodivergence, but also kind of a metaphor for him masking and maybe sort of about his internalized ableism? Which is complicated, but hey, that's how being ND is sometimes.