Unbound by Lori Devoti

Book 1 of the Nine Worlds (previously Harlequin/Silhouette Nocturne Unbound series)
Risk Leidolf is a hellhound—a legendary, otherworldly creature who is both man and beast. For centuries, the shapeshifter has been bound to serve an immortal witch. But after being ordered to destroy novice witch Kara Shane, the man within him rebels. And the beast the witch seeks to unleash is held at bay—for now.

Fiercely drawn to each other, Risk and Kara set out to find her missing sister and soon form a passionate alliance. The power of the twin witches could free pack alpha Risk from the immortal witch’s bondage, but that freedom may come at a steep price.

Will love win out, or will others convince the unlikely pair that their love is a lie and their only choice to survive is to betray the other?