There are almost 2 separate story lines in Darelle's Trinity.
One story with Seigneur Lascaux a vampire and lord of the estate ends up imprisoned after biting Darelle and turns into one whose heart never stops beating.
Darelle, the damsel, leaves Lascaux and is with Kane and Gareth learning the ways of "Les Coeurs Eternels", which is basically learning how to pleasure each other as a threesome.
Then they have to help Lascaux escape prison because his lover Serge requests it of them.
Time lines and flow is sometimes hard to follow, that's why I give this story a 2.5.
Darelle was brought across by the world's oldest vampire, yet she retained her soul.
Terrified by her sire's obsession with her, she escapes him and is rescued by two gorgeous Roman warriors. Not only do they rescue her, but Kane and Gareth claim to be her guardians, fellow vampires of her breed, sworn to pleasure, love and protect her for eternity.
True to their word, they shower her with erotic pleasures beyond imagining, their union strengthening them against the forces they must face. For an evil far greater than her sire's lust awaits them all…