Vera Hall

When Vampire-Demon Sam Kyllwood discovers he's the keeper of some mysterious circle, he laughs it off. When he finds out that his younger brother is supposed to fight to the death in said circle, he snaps right to furious. And that's before he starts uncontrollably making things explode - it turns out it's never too late to develop deadly new immortal abilities. But even those explosions are nothing compared to what happens when he tries to handle a very suspicious, brilliant, and beyond sexy human female.

For too long, Benjamin Reese has masked his deadly skills and temper with loyalty and humor. A vampire-demon hybrid, he fiercely protects his family, guards his brothers, and destroys the enemy without mercy. But when he discovers one fragile, beautiful blonde - a woman once mated to a Kurjan, no less - every primal instinct he has buried for centuries roars to life. With the mating mark she roused on his hand entwining their fates, no one will prevent him from keeping her safe and making her his, forever.

Though he has vampire, demon, and Viking blood rushing through his veins, Ivar Kjeidsen's soul-crushing trip to hell broke him in ways he can barely fathom. One vow keeps the deadly immortal standing: To rescue the vampire brother who had sacrificed freedom for him. To do that, Ivar needs the help of a brilliant physicist with wary brown eyes, fierce brilliance, and skin that's way too soft. Dr. Promise Williams understands the underpinnings of the universe but has never figured out the human beings inhabiting it. Her function is to think and not feel, until she's touched by a vampire.