You could technically "start" corrupting Cait by having her study the Rimebound Grimoire you can buy from Senja (one of Evergreen's daughters, the one on the furthest square of the mansion), and then giving her the Rimescore after obtaining it on the Drifa quest, but the changes are mostly flavor text, and the corruption doesn't play that big of a role outside those two mentions
Ryn is another interesting case, since you can't corrupt her in the traditional sense, but you can be a bad influence to her and make her more dependent on you. Just keep her at low confidence by being a dick to her and at high libido by teasing or sexing her "hard" often and you'll eventually get yourself a sub that depends on you and wants to be used. Bonus points if you manage to turn her into a buttslut and keep her caged even after undoing the seal of the chastity cage
You can also corrupt Azzy by two easy ways: 1- be an arse and kick her and Lian into the milk pool, turning both into braindead bimbos, but you'll lock yourself out of being able to recruit her. or 2- AFTER cleansing the hive, have a chocker build from the corrupted honey core you get after the quest, and once she equips it, she'll start behaving like the hornets did before you cleansing the hive, but with a bit more on her nogging, or at least enough to let her fight alongside you
The best example would be Viv, since you can literaly turn her into a demon before recruiting her. To do it, just don't tell her where did you get the weird milk you give her to test, and once everything is ready, you'll have a blue demon witch to fight at your side
Honorable mention would go to Brint, who you can literaly genderbend and who seems way too calm for someone whose body is changing and can't do much to stop it. Just get him to wear the golden armor in the cave near the Marefolk village and ignore every warning the game throws at you about something being wrong with your hypermasculine bull friend, and you'll eventually end with a submisive and breedable cowgirl
