That's what I thought too. I also find it kinda suspicious that she keeps trying to get close to Rururia when she could literally be friends with someone else instead of continuing to pester Rururia when she already told her she doesn't want to be friends. I'm thinking that in the world Irene isekai'd from probably had something like "In the original plot, Rururia was the only friend the villainess, Irene, had. I need to become friends with her." or something because it really seems like that is the case...
Doesn't rururia fills more the hole of the heroines? Not personality wise, but looks wise.
That girl who faked falling from the stairs seems to have just copied her hairstyle and all.
irene is probably isekaied cause she used some japanese slangs so i dont trust her for one bit.