Synopsis: Some people are born with special powers and they are called something in the book. The main character is one of these somethings and their power is essentially super-strength and is the daughter of the king. Therefore, she is forced to basically do his dirty work for him. I remember that, at one point, the main character (I think her name was Kristin) falls in love with a prince (named Rowan?).
Genre: Young Adult Fantasy
Read: Probably 10 years ago.
Publication: Also probably 10 years ago.
Book Details: Hardcover, written in English
If I remember anything else, I'll edit it in!