I feel like it could be cool if an adventurer was corrupted wholly, they get turned into a monstrous form, and are still rescuable, but of course their new forms give them new drawbacks, but also potential buffs, depending on what they become (probably based on what crests and personality they got). also would be neat if demons were in the game, probably the ones that cause humans who become wholly corrupted to match their inside to their outside (meaning they aren't necessarily evil, but certainly not something humans would like either...) . it's not like they'd lose their memories or sense of self or anything, unless you wished that to be the case, mainly that their corrupt inside now matches how they look on the outside, just my opinion. probably would coincide with what crest they focus on, like servitude with spiders since iirc spidergirls are the ones who try to make people more servitude focused. probably the monsterization would happen most commonly if someone is captured for a long period of time, though it probably isn't impossible to happen in other ways. could be something a boss inflicts if you do something that's been explained in the lore that the boss has control over. like if a boss were a rancher robot, with the cowgirls, though that was just an example I thought of.