Circle of Shadows by Evelyn Skye

Sora can move as silently as a ghost and hurl throwing stars with lethal accuracy. Her gemina, Daemon, can win any physical fight blindfolded and with an arm tied behind his back. They are apprentice warriors of the Society of Taigas—marked by the gods to be trained in magic and the fighting arts to protect the kingdom of Kichona.

As their graduation approaches, Sora and Daemon look forward to proving themselves worthy of belonging to the elite group—but in a kingdom free of violence since the Blood Rift Rebellion many years ago, it’s been difficult to make their mark. So when Sora and Daemon encounter a strange camp of mysterious soldiers while on a standard scouting mission, they decide the only thing to do to help their kingdom is to infiltrate the group.Taking this risk will change Sora’s life forever—and lead her on a mission of deception that may fool everyone she’s ever loved.