#k!af2

AF vamp AU actually centers itself around AF1, largely before the timeloop even begins. due to a lot of like scientific stuff regarding pointification + the lore of the first loop in K!AF2 (which my AUs are based on, just my interpretation/writing of AF as a whole) it would take a while for the loops to begin, if they ever did. mason would then instantly sniff claud out as being weird due to their excess of star power lol! no need for ss1 to infodump!

one thing about anshine is that, due to being the first point cyalm ever made, they're very poorly made. like. there are so so many oversights, just purely biologically. in the vamp AU that issue would be exacerbated because star power vampires are not something cyalm/the red X was at all familiar with before trying to turn one into a god. they would absolutely retain their vampirism, and it would wreck them mentally even worse than it did mason...

you're completely correct that anshine, both in this au and in K!AF2 generally, hides things to maintain a perfect image of themselves in order to not worry others! they're not good at it but they try! being around literal star deities does numbers on their hunger. they're always craving it. it makes them feel like a monster. they have tried to feed on themselves many times and the results are pretty unpleasant

i think the other points would quickly notice something is off, especially those that knew anshine for longer, namely ixol, ulipse and shallare. it would be really hard to discern exactly what until it's too late though i have ideas for some almost-cannibalistic outbursts they'd have around these three during the early plot, but that's still up in the air... besides those fun little events, they wouldn't really shun anshine for it or anything. absolutely not their biggest problem when cyalm exists - anshine cannot physically drain most of them to death (shallare is an exception with solgon and ploque being the next closest to that danger)

as for stratos, i think they'd would very much want to go back to that voluntary feeding arrangement you mentioned, especially because it'd give them a sense of normalcy/gaining their old life back, but anshine would avoid it like the plague for fear of what might happen. if they accidentally hurt or stars forbid killed stratos because of their hunger...