First Drop of Crimson by Jeaniene Frost — book slip

Denise MacGregor knows all too well what lurks in the shadows—her best friend is half-vampire Cat Crawfield—and she has already lost more than the average human could bear. But her family's past is wrapped in secrets and shrouded in darkness, and a demon shape-shifter has marked Denise as prey. Now her survival depends on an immortal who lusts for a taste of her.

He is Spade, a powerful, mysterious vampire who has walked the earth for centuries and is now duty-bound to protect this endangered, alluring human—even if it means destroying his own kind. Denise may arouse his deepest hungers, but Spade knows he must fight his urge to have her as they face the nightmare together. Because once the first crimson drop falls, they will both be lost.