The Darkest Whisper 1 (Lords of the Underworld #4.1)

Gwen's the vessel of the legendary creatures called harpies and, because of that, was caught to be experimented on. Then one day, a brawny warrior by the name of Sabin appears and releases her from her glass cage. Unfortunately, her sense of relief is short-lived. Sabin, in the distant past, suffered the wrath of the gods, and had sealed within him a terrible, dark and suspicious warrior. He wants to use the harpy's natural prowess as a killer, and so takes her back to his castle. There he tells her that she is now his, and he carves his mark into her neck. Gwen bounces between feelings of anxiety and attraction...