" It is an old tradition,” he began. “Even among the fey. A lady asks a warrior to become her knights, her chosen protector, for as long as they both draw breath. Only those with royal blood can enact this ritual, and the choosing of a champion is something only the lady can do. But it is the ultimate show of faith between the lady and the knight, for she trusts him above all others to keep her safe, knowing that he would lay down his life for her. The knight still obeys his queen and court, to the best of his ability, but his first and only duty is to his lady. "

― Julie Kagawa , The Iron Queen (The Iron Fey, #3)