Crown of Crimson (The Afterlight Chronicles, #1)

First Rule of the Cannon: Trust no one. Aerietta Elony is destined for evil. Born into a royal family, it was quickly discovered that she bore the Jezdah mark - an intricate tattoo meant to identify the Children of the Elements. To make sure his people never knew about the danger that hid in their midst, the king had his daughter sent to the leader of the Cannon, his order of assassins, where she would learn to become one of them. No one was ever supposed to know what Aerietta was, where she came from, or what she was destined to become. She's never worried what would happen if someone discovered her secrets. But when a neighboring kingdom attacks, and Aerietta is betrayed and captured, keeping her secret will mean the difference between life and death. When the king of the neighboring land enlists her services to track down one of her traitor companions, she has no choice but to accept. But in order to find her former friend and make it back to the king with her head still attached to her shoulders, she'll have to keep the enigmatic, inhuman Swordmaster in the dark, which proves to be more difficult than she could ever imagine. Deception abounds, danger is just as prevalent, but even in this world of demons and magic, the only thing Aerietta fears is herself. The Queen of Crimson accepts.