Bound to the Hellhound by B.A. Stretke

He was worthless to his family. To a Hellhound, he’s everything.

Theo Tuffin has always lived under the thumb of his brutal father and older brothers. Invisible, ridiculed, and constantly abused, he’s spent his twenty years chasing an approval he knows will never come. But when his family’s shady business deal goes explosively wrong, Theo finds himself battered, bloodied, and trapped in the office basement—the ultimate sacrificial lamb.
Valerian Keller is a tortured soul, a powerful Hellhound who carries the scars of nearly a century spent in a pit beneath the fires of hell. He believes a long life of duty and isolation is all he’s fit for—until he accompanies his Vampire Master to a meeting in Detroit.
Valerian doesn’t walk into a negotiation; he walks into an atomic blast of Fated power. An agonizing cry tears through his consciousness, pulling him across floors and through shifting guards. Down below, he finds a delicate human, beaten and terrified, whose scent claims him entirely. In his wake, Valerian has set a powerful, vengeful wolf shifter family on a path of revenge. They want Theo’s head for payment, and his own brothers are hunting him.
The Hellhound who never wanted a mate must now start a war to protect the small human who has melted the ice around his hell-scorched heart.

Fate always finds a way.