Immortal Bastard by Lydia Michaels

There is nothing more sacred than the immortal vow of bonded mates, but when Delilah Starling is transitioned against her will and taken captive by a savagely beautiful immortal, she pledges to fight his dominant rule to her last breath.
Christian Schrock, an elder of The Order, hunted and possessively claimed his mortal mate as was his right. His irrevocable actions, however, sparked challenges he never anticipated.
Subjected to live under the patriarchal reign of an ancient society, Delilah battles the oppressive traditions forcing her to submit to a life she did not choose, and a man she does not love. Christian must convince her that she belongs to him, but the unruly female refuses to see past the brutal betrayal that founded their relationship.