Fire by Kristin Cashore

It is a world of Monsters. Beautiful creatures with bright hair of all different shades and colours, and (if you're not careful) a tendency to lure you into your doom. But there is only one human Monster left and she goes by the name of Fire. Beauty is not Fire's only power, for she can see into your mind and convince you to do as she pleases. But this is not something beautiful for Fire. She's hidden from other Monsters her whole life--both creature and normal human alike. But as her world is preparing for a war, she knows she needs to help her King. The King that is in love with her beauty and her magical allure, but not her. Fighting with her inner demons, she has to find a way to help the King, while also not using her mind powers for anything more than protection.