Dark Stranger by I.T. Lucas
When Syssi's paranormal foresight lands her a job at Dr. Amanda Dokani's neuroscience lab, it fails to predict the thrilling yet terrifying turn her life will take. Syssi has no clue that her boss is an immortal who'll drag her into a secret, millennia-old battle over humanity's future. Nor does she realize that the professor's imposing brother is the mysterious stranger who's been starring in her dreams. Since the dawn of human civilization, two warring factions of near-immortals - the descendants of the gods of old - have been secretly shaping its destiny. Leading the clandestine battle from his luxurious L.A. high-rise, Kian is surrounded by his clan, yet alone. Descending from a single goddess, clan members are forbidden to each other. And as the only other immortals are their hated enemies, Kian and his kin have been long resigned to a lonely existence of fleeting trysts with human partners. That is, until his sister--a neuroscience professor and a leading researcher of paranormal abilities--makes a game-changing discovery. The Children of the Gods is a continuing saga and is best read in order.