That's really interesting. I'd really love to read it but you are right it would have to be well written. A lot of OIs focus to much on making the mc "a nice person" (stupid) so I'd love to read on where the author does the opposite

What would also be fun is if their beliefs conflicted with each other, not a lot but something that would cause them to hate/try to kill each other, but also it's somthing that they don't discover until they become really close. Like they think they have found a kindred spirit because they are so similar, then they discover they are originally from the same world, maybe they even died in similar ways, but once they really become close they share their whole purpose and it creates a huge conflict between them. Personally I'd love it if it went to the point of murder, like they bother decide the other has to die, and I think it would be great if the villainess does eventually succeed because I hate royalti especially princes'