Red Kiss

Read Deidre Knight's posts on the Penguin Blog.
The spartans wage fierce wars-but nothing matches the battle within their hearts...
Spartan slave River Kassandros can transform into any weapon. After a bloody battle he's forever a dagger-until a mortal can release him. Drawn to this blade, Emma Lowery draws blood with it and frees River. But even as they fight off intense passions, a sinister power arises to destroy them. To protect humankind, they may have to make the ultimate sacrifice-and lose their chance at love...