A Hunger Like No Other by Kresley Cole

After enduring years of torture from the vampire horde, Lachlaine MacRieve, leader of of the Lykae Clan, is enraged to find the predestined mate he's waited a very long time for, is a vampire. Or partly one. This Emmaline is a small, ethereal creature half Valkyrie/half Vamipire, who somehow begins to soothe the fury burning within him. Sheltered Emmaline Troy finally sets out to uncover the truth about her deceased parents~until a powerful Lykae claims her as his mate and forces her back to his ancestral Scottish castle. There, her fear of the Lykae and their notorius dark desires ebbs as he begins a slow, wicked seduction to sate her own dark cravings...