Dark Vow — Kristi Avalon

Kara Holden's determination to save her father's life plunges her into the secret underworld of a werewolf empire on the brink of war. The sexy, enigmatic Scythe has sworn a vow to her father to protect Kara no matter the cost. Because she is the key to their survival. Despite her internal struggle to believe in the impossible, Kara must accept her ancient lineage to unite the clans as Scythe's destined Mate. Before the bloodmoon rises, Scythe initiates Kara through the sexual Rite, turning her Halfling status into full Lycan. Together they battle for their destiny, her father's legacy, and their immortality.

(Note: this book was previously published under author's pen name Kristi Avalon)