They're insane. And the best thing is? They're insane for each other. Whatever crimes one does, I'm sure the other would forgive them. They're mentally unstable, but it's understandable. There's one sane and good prominent character and it's the maid and I feel sorry for her. I'm also worried our two main characters will not meet with a happy ending, but I hope that's not true.

I usually don't like possessive, yandere love interests, but I'm perfectly fine with Étienne because Sioanna feels the exact same way about him. It's reciprocal, not a one-sided power imbalance where he's lying to her about his true character.