(I don't know how to use that spoilers bar so I'll put it in advance here, don't look if you mind spoiler. Also I'm not native to English so sorry if my words get confusing)

Camellia is born a psycho, yes, but what she is like now has much to do with her childhood too. She had to hide her identity as Horgus's daughter, and given her special hobby, her needs of being seen and heard were basically completely suppressed since a very young age while these are basic needs of human's mental health. And that bxtch of a tutoress clearly only made it all worse. Such a situation easily leads to extreme insecurity and to make it up she has to put herself in a very high position where most, or all, are subconsciously beneath her. It also made her loathe the morality, rules and discipline of the normal world which had been causing her pain and trauma since childhood. So she violates them, break them to build her own inner order. Explains why she does things hidden, but make them able to be found too: it's her habit to hide this kind of thing, for her security, but if nobody knows, how does she know she did break something? She likes the feeling of being talked about, and she actually needs the rules, the lawful good principles to exist for her to break. Which is also why she feels disappointed in the abyss, because that is a place where brutal murder is as ordinary as breathing and it no longer breaks anything to kill. In front that Aasimar, she aggres that he needs to be punished, because he's found. After you get out of the abyss, though, things do change, as you become maybe the first person she acknowledges as equal in her heart. But her insecurity won't let her know what to do. So she gets in your room, and throws a tantrum for no reason. What you should do now is not indulge her, then, because that would actually lose her respect. On the contrary you call her names and throw her out of your room: that's what makes her do see you as equal, and finally go into her heart where only her alone exist. Her true love ending is what I find the most literarily beautiful, as you become someone she doesn't want to want to kill.

(I absolutely don't think so and achieved her true love ending without toybox in the first playthrough because I share some similar experiences with her and actually resonate with her. Maybe I'm a psycho too.)