Infinity is a novel written by Maggie Shayne. It was first published in 1999 and is the second book in The Immortals book series.
Description[]
For five centuries, Immortal High Witch Nicodimus has been suspended in an eternity of darkness. His heart was stolen away in the ultimate betrayal by his love Arianna... Now Arianna discovers a way to bring him back. But the power that returns Nicodimus to her arms also summons an ancient enemy. To fight this dark danger, they must confront the past--and reclaim infinity...