Keeper of the Fallen - The Keeper Trilogy, #1

"The spirits have placed a very important task in your hands."A massacre. An escape. Sonika could have been a warrior and a leader if she hadn't been ripped from her homeland as a child. As the last of the Okami, she will never stop fighting for her right to live. Stalking the shadows is the only world Kulako knows. Heart filled with hatred, death by his blade is inevitable, but who he is beneath that darkness longs for something else.
When a twist of fate forces their lives to collide, their choices may be enough to hold back the merciless coils of the Giahatio. But not even the will of the Gods can stop the will of the Emperor.