(I hope this makes sense)I think part of it is that Ian seems to tailor his revenge to the person he's targeting. With Michele, it's especially psychological and emotional because Michele wears his heart on his sleeve. He genuinely loves Ian, trusts him and makes no attempt to hide his feelings. So imagine being in his position...the person you're opening your heart to is also the person manipulating your trust and affection. It might not look as bad from the outside, but experiencing that betrayal from someone you genuinely love is a different kind of hurt. And I think that's what makes their dynamic so disturbing.
I'm reading the noble, and Ian just toys with Michele's emotions, the way we have been seeing. He thinks of doing terrible things to him, but he isn't capable.
Or is it just the beginning?