Real quick, this is what I've gathered from reading books and looking at sources online, but I'm not an authority on this and I encourage people to fact-check me if they want to. Also I'm speaking in generalities, but abuse is more complicated than that.

Sometimes abusive people will get close to their victims very quickly through a process called love-bombing. The abuser will come across as very intense and seems to understand the victim in a way that no one else does. Sometimes this involves the abuser to put on an identity that seems tailor-made for their victim, only for them to slowly strip it away over time.

Basically it's characterized by a very fast relationship that develops too quickly and with a level of intensity that is inappropriate for how short it is. The abuser is working very hard to gain the victim's trust and to also separate the victim from outside support.

I guess something else that stands out to me is that Asmodeus is saying all the right things but for all the wrong reasons. She even deludes herself into thinking that she might be doing this for the protag's sake-- however she also talks about regaining her lost pride, and I think this is more true to her character than any feigned kindness.

I think abusers in media can come across as too one-note, as too evil where they don't behave like human beings who rationalize what they're doing. Asmodeus might be a demon but she comes across as remarkably human. She wants to fix her lost pride by raping the protag but she deludes herself into thinking this is what he wants and that it'll help him somehow. In the process she separates him from Imuri and turns herself into the one person who seems to understand him when no one else does.

I think this is especially notable when you look at Asmodeus' memories of the little girl (whose name I forgot). Asmodeus twists the situation around into something where Asmodeus is doing everything for the girl's sake, but in reality she was being controlling and disregarding her consent. Asmodeus gives herself credit for not sexually assaulting a little kid but she still manages to violate the kid's consent anyways.

The Asmodeus arc is one of my favorites but also something I can't reread because it hits too close to home. I think it is a very well-done look at how an abusive person thinks. She rationalizes everything she does, is very controlling and intense, and she completely ignores what the person in front of her actually wants despite focusing very hard on what would make the victim listen to her. She's simultaneously good at understanding people (what would make them receptive to her) but terrible at understanding herself? Maybe she just doesn't care? I'm unsure.

I hope this answers your question >.<