So I has an idea for an undertale infection AU.
So this was specifically inspired by
@shadowy-suitcase-herring-neck 's infection AU, but you can imagine it with others.
(TW talk of disease, death, bites, and apocalypse stuff!)
So, Lust Sans. We all know that monsters in Underlust weren't always, well, Lustful. That's due to the fallen humans soultraits, of Lust, right?
While I'm not entirely sure if this is fanon/canon, but we know about the vaccine, yeah? The one thar made monsters lustful.
Well, hear me out. Since there's INFINITE AUs, I think it's pretty obvious that atleast SOME of the Sanses would be immune to the infection, atleast until the virus mutates itself enough to be powerful enough to infect, said Sanses.
I think it's like a tier list. The first variation could infect a small portion of Sanses, with a few being immune. But that few could be infected by the second tier, which couldn't infect third tier immunity, do you get what I'm saying?
I think people like Reaper sans, would be 4th tier immune, only a VERY strong strained could infect a literal God. People like Six-Bones would have 3rd tier immunity, so still pretty strong.
And, I think people like Lust would have that lowest immunity, 2nd tier, where they're safe from the first variation of it. The reason why, is because his soul has that Lust vaccine in it. And I think the vaccine has more crap in it than just pure Lust, I think it'd be like a wall to the first variation of the Virus..
Woah, did I just accidentally create an AU? Cool.
ANYGAYS—I've depicted what I think that'd be like, here's a sketch of Lust, with two bite marks. Now clearly, he's not infected, but I think he's fully aware that he won't be immune for long. Especially if it's Lust from Shadowy's infection AU, they confirmed they think a medic role would fit him. So I think he'd have some medical knowledge.
Thus, I think he'd wear a muzzle with a mask underneath. But the muzzle was created SPECIFICALLY so he couldn't take it off himself, it requires tedious help from another person.
He knows, that he's not gonna survive this if they don't make a cure, NOW. He doesn't know why he hasn't turned yet for sure, but the idea I just presented you is his main theory. But he knows that if any of the other underlust survivors get it, (I'm saying the only survivors are him, mettaton, and frisk) than he'd be at risk too.
...For now though, the muzzle is a precaution, keeps him from being able to bite anyone.