I just randomly remembered this book yesterday but can't think of the name or the author and it's driving me crazy. Things I remember about it: - the brother and sister were some kind of royalty/nobility and were separated early in the book - it was graphically violent - the sister had a shape shifting cat companion who the brother has a crush on - the cat's name might have been cherry or something? - at one point the brother hooks up with a woman who has a pig tail - I'm pretty sure there's a part where the brother is restrained for a long period of time and has to poop, and goes on about how you never think of people having to poop in survival situations? I would have read this book some time around 2008 (or earlier), so it wasn't published any time recently.

I would really appreciate if anyone could help me figure this out!