Ahaha, you have totally sold me on Mononoke. I think I also love the feminine unconscious thing too.

I like stories about interdependent sibling relationships

Hehe, if you did read into the later arcs in the Saiunkoku novels, I wonder if you would like them, because Saiunkoku is chock full of that kind of sibling relationship. I know the anime didn't work for you, but like most authors, she gets better as she goes on, and it does include much more violence/twistedness/intrigue.