Lords of the Darkyn Series by Lynn Viehl, Johanna Parker

The High Lord of the Immortal Darkyn has sent his most trusted warrior, Korvel, to retrieve a coveted scroll that's rumored to contain maps to Templar treasures and the secrets to eternal life. Uniting with Korvel to recover the dangerous artifact is Simone Derien, the daughter of the scroll's guardian, and a woman with many deadly secrets...

Jamys Durand has survived being made an immortal Darkyn, horrific torture, and years of grueling warrior training. But he has no future to offer Chris, the mortal woman he loves, without his own territory. When he learns of a lost Templar treasure, Jamys vows to possess it and win his lady's heart.No one knows Chris Lang wants to be a tresora so she can live with Jamys, her secret love. Her superiors offer to make her dream come true, but only if she finds the lost treasure before Jamys can... moreJamys Durand has survived being made an immortal Darkyn, horrific torture, and years of grueling warrior training. But he has no future to offer Chris, the mortal woman he loves, without his own territory. When he learns of a lost Templar treasure, Jamys vows to possess it and win his lady's heart.No one knows Chris Lang wants to be a tresora so she can live with Jamys, her secret love. Her superiors offer to make her dream come true, but only if she finds the lost treasure before Jamys can. Working together, Chris and Jamys track the jewels through a shadowy maze of priceless artifacts, decadent secrets, and one ruthless opponent who can possess an immortal's mind . . . and will stop at nothing to have Chris. less

Beaumaris of York has many secrets. No human can know that he’s an immortal Darkyn assigned to Knight’s Realm, the Kyn stronghold disguised as a medieval theme park. And none of his brethren can discover that he’s a half-breed, rescued from slavery as a child. Lately Beau has been yearning for action—and he’s about to find it with his new mission.Brilliant archaeologist Dr... moreBeaumaris of York has many secrets. No human can know that he’s an immortal Darkyn assigned to Knight’s Realm, the Kyn stronghold disguised as a medieval theme park. And none of his brethren can discover that he’s a half-breed, rescued from slavery as a child. Lately Beau has been yearning for action—and he’s about to find it with his new mission.Brilliant archaeologist Dr. Alys Stuart is infamous for her extraordinary theories—especially those concerning the mysterious Knights Templar—and she is unaware that her research is funded by the Kyn coffers. When the Kyn sends a vexingly good-looking man to assist—and protect—her, she doesn’t expect the surge of attraction she feels for him.When a powerful Templar artifact surfaces, Alys and Beau must trust each other enough to stop mankind’s greed for immortality from sparking a war between mortals and Kyn that will destroy the world. less