Demon’s Trust by Raven Dark

Can a love that defies all odds survive?

Detective Cassidy Morgan is no stranger to the supernatural. She’s been using her psychic abilities to search for her missing sister for years. But when a mysterious swordsman rescues her from a vicious attack, Cassidy realizes the sexy, possessive, knight in not-so-shining armor is the only one who can help save her sister.
When Arcayos D’Karian, former servant of the Lord of Demons, is chosen by the Goddess to protect the human race, he accepts the rules: never expose the supernatural monsters, never tell anyone who (or what) he is, and always fight—and be—alone. Until he crosses paths with beautiful, fiercely independent Cassidy, and all the rules change. She doesn’t just seem perfect, she’s his fated mate.
Cassidy’s willing to deal with Arcayos being a demon, but her entire police force is convinced he’s a serial killer and even she wonders if his demon-hunter role is just a cover for murder. With her sister’s life on the line, trusting him is a risk worth taking.
Is eternal love their destiny or will it destroy them both?