Vampire Runner by Rowan Hart

Torn apart by a demonic deal 150 years ago, I race to complete the bargain before the woman I love is lost forever.
Cassandra’s pact with Eris was a sacrifice to save the Nightshade Vampires. Since that fateful night, I’ve endured the agony of safeguarding the demon possessing my destined mate’s body. Tortured by my own dark desires and base cravings.
Vengeance was vowed to the demon Eris and we close in on the archangel Aeternaphiel. Only for him to slip through our fingers after delivering a devastating blow that slowly steals Cassandra’s life away.
Time is a luxury my mate doesn’t have and I refuse to lose her. I’ll finish this fight started centuries ago, because if I don’t, Cassandra will die. It will take the combined deadly skills of the entire Nightshade clan to destroy the archangel and save my mate.
But when a devastating truth surfaces, it threatens to splinter the Nightshades. My king faces an unimaginable decision between our clan and my mate. For me, there is no choice. There will only ever be Cassandra.
The rest of the world can go to hell.