(a cheat sheet!)
TANTALIZE (#1) is the story of Quincie P. Morris, a teen struggling to help save her family's Italian restaurant by re-launching it with a vampire theme. It's a great idea until some real vampires show up and her best friend, Kieren, is suddenly suspected of murder.
ETERNAL (#2) is the story of Zachary, a guardian angel who "slips" when he breaks the rules of heaven in an attempt to save the girl he loves and that girl, Miranda, who becomes a vampire princess.
In BLESSED (#3),
the casts of TANTALIZE and ETERNAL
crossover as Quincie attempts to foil the vampire who remade her in his plot
to raise hundreds as undead.
DIABOLICAL (#4),
is the last of the novels featuring Quincie, Kieren, Zachary, and Miranda. The heroes join forces in a battle that begins in a devilish school and rages from heaven to hell.
TANTALIZE and ETERNAL may be read in either order, but the author's intent is that TANTALIZE comes first for the reader, even though ETERNAL is set first in time.That said, all of the novels have their own arc with a beginning,middle and end, though BLESSED is more of a sequel to TANTALIZE, and DIABOLICAL is more of a sequel to ETERNAL.
The graphic novel TANTALIZE: KIEREN'S STORY, illustrated by Ming Doyle, covers the same events (and more) as TANTALIZE, retold from Kieren's point of view.