Jeweled Fire by Sharon Shinn
As one of the four princesses of Welce, Corene always thought she might one day become queen. Only circumstances changed, leaving fiery Corene with nothing to show for a life spent playing the game of court intrigue--until a chance arises to become the ruler of a nearby country. After stowing away on a ship bound for Malinqua with her loyal bodyguard, Foley, Corene must try to win the throne by making a play to marry one of the empress's three nephews. But Corene is not the only foreign princess in search of a crown. Unaccustomed to being anyone's friend, Corene is surprised to find companionship among her fellow competitors. But behind Malinqua's beautiful facade lie many secrets. The visiting princesses are more hostages than guests. And as the deadly nature of the court is revealed, Corene must rely on both her new allies and Foley's unwavering protection--for the game she has entered is far more perilous than she ever imagined...