Immortal Montero Series by Greg Mongrain

Young billionaire Sebastian Montero has hunted killers for seven hundred years, the murder of his baby brother still haunting his dreams. After a teenage girl is ritually butchered, Sebastian joins the LAPD in their search for the man known as "The Voodoo Killer." When Sebastian is nearly strangled by malevolent spirits invading his home, he realizes his target is a man with formidable magical powers. But he doesn't know how dangerous the Voodoo Killer has become.

After accepting Sebastian’s proposal of marriage, Aliena passes out in a feverish swoon, leaving Sebastian to wonder if she will ever wake. What began as a dream come true for Sebastian devolves into his worst nightmare as Aliena forgets who he is, unconcerned over what has happened to her. When it becomes apparent she is the most likely suspect in a spree of vampire murders, Sebastian is desperate to keep the other vampires from executing her... moreAfter accepting Sebastian’s proposal of marriage, Aliena passes out in a feverish swoon, leaving Sebastian to wonder if she will ever wake. What began as a dream come true for Sebastian devolves into his worst nightmare as Aliena forgets who he is, unconcerned over what has happened to her. When it becomes apparent she is the most likely suspect in a spree of vampire murders, Sebastian is desperate to keep the other vampires from executing her. But Aliena is inhabited by one of the Ghosts of Atlantis, an interdimensional entity that burns its victims to dust—and will eventually consume his beloved Aliena from the inside out if he can’t extract it in time. less