When Earth's population drastically increased, humanity attempted to colonize Mars. During the colonization, they discovered two alien technologies: the Bacillus and the Crusnik nanomachines. The colonists installed the Bacillus in their bodies which transformed them into Methuselahs. They installed the Crusnik in the bodies of four test tube babies: Seth, Cain, Abel and Lilith whose enhanced bodies were the only ones able to survive the procedure.

When the colonists returned to Earth, a war broke out between the Methuselahs and the humans who had remained on earth. Abel, Cain, and Seth took the Methuselah's side—while Lilith supported the humans' side. The continuing war eventually led to "Armageddon," the apocalyptic event that happened 900 years before the start of the story. During the war, Cain went insane and killed Lilith. In grief, Abel took her body to the Vatican where she was buried. Abel remained at her side, weeping for her, for 900 years.

At the start of the story, the vampiric Methuselahs, still a major political and military force, continue to wage war on the "Terrans," as they call regular humans. The Roman Catholic Church is a major military power determined to protect humans from the Methuselahs, with its seat of power based in the Vatican. The Methuselahs have their capital of Byzantium, which is surrounded by a field of particles to filter out UV radiation, protecting the Methuselah population.