If you really wanna know, I can discuss some of it since I am free now.
Juno by herself isn't so much of a pervert, she pretty much only has hots (or is it colds?) for a certain wandering swordsman with a chronic case of harem MC syndrome, much to the dismay of his supposed canon OTP. The problem is that, according to
@TheWindel half of the multiverse wants to rape the poor snake in some shape or form.
As long as you keep Diana away from her dear mistress, she'll only have eyes for Bastion. If you add Victoire into the mix, things get complicated. The only thing worse is of both Bastion and Victoire are on out at the same time. Depraved dragon girl is really depraved. Also, avoid hellhounds and plant monsters, at all costs.
Iona doesn't smut, period. Unless out has to do with a certain Dr. Epsilon. This can change if it's her young/alternative self, though.
Victoire would take anything that strikes her fancy to bed regardless of the other party's opinion on it. That said, she has her favorites, a list that is always prone to expansion. Her acceptance changes quite a lot when she's on the receiving end.
Ni-Mu doesn't have the personality to lewd things. Even if she tried it wouldn't be more interactive than doing it with a doll.
I'll think ok the other characters later can't come up with anything now.