In this YA novel, Isabel is supposed to be an immortal guardian of kings, but she remembers little about what she was doing before Prince Rokan dragged her out of the forest where she'd been hiding for ten years. Moreover, she's supposed to be a shapeshifting immortal guardian and hell if she can figure out more than hair color changes and 'now I have low light vision'. Also, she doesn't remember why she was in the forest in the first place when she was supposed to be guarding the royal family.
This book really didn't work for me. Isabel learns pretty quickly the reason her master, Prince Rokan, and his sister, Clarisse, are so cagey around her is that Rokan's father killed the last king Isabel served and she went missing trying to guard the last king's kids. Rokan is a bit of a romantic twit, so he assumes that he can control Isabel via invoking the spell that bound her to the previous royal family -- and, a bit more sensibly, that having the old royal guardian around legitimizes him as the new king. (Clarisse thinks this is a terrible idea, of course.)
Then one of the last king's kids, Kaer, turns up and suddenly Isabel has two targets she wants to protect, both of whom want the other dead, or at least out of the way of the throne. And here I start thinking that rulership by the firstborn son of the last guy in charge is a stupid system. The author does her best to make me want to root for Rokan instead of Kaer, but it falls flat, since basically you have 'the bitter one' versus 'the idealistic one (who would rather be riding)'. The thing that finally sways Isabel is the backstory about Kaer's sister, and that he resents Isabel for not saving him... but I still don't care.
Actually I want Clarisse on the throne, since she was the most interesting and smartest character in the book, though that could be since the narrative (and Clarisse herself) went to great lengths to conceal her true allegiance and capabilities.
So this one goes into the 'get rid of' pile which I need to work on actually getting rid of.