Honestly, when I was reading this book I always felt like I was starting after book one and it was confusing. But it's always been on my mind, so I want to figure it out and clear up the confusion and re-read it.
I remember the main character is a girl. But there is a side male character and he was supposed to be the main character's brother. But for some reason, things got changed and he wasn't. I don't remember a whole lot about this book, although I know at the end some kind of dimensional creature absorbs a dragon and a unicorn. And then the side character takes the girl and some other people to another dimension until it is safe.