According to legend, Cain was one of the first humans, and the first to be fully touched by Emmanuel. The exact circumstances behind the situation are no longer known, but it seems Emmanuel’s touch had a powerful effect on Cain, tainting him with backlash, and infecting his soul, such that Cain became the first undead creature, and father to all the others.
His reign of terror was stopped millennia ago through the use of a legendary magic weapon that severed his hand and sent him into a dormant state. The hand disappeared shortly thereafter.
In this era, Cain’s body was held in protected storage by Magitech Corporation until very recently, at which point he was reunited with his lost hand and reawakened. He escaped to Mars and wreaked havoc there until he was once again stopped using the same sword of legend.
William Moss then performed a ritual to cleanse Cain’s undead essence by transferring it into himself.
Cain, left with the alien nature of Emmanuel but without the undead taint, has been deemed suitable for the Deus rite – a process wherein Cain is infused with a gestalt consciousness composed of many souls called the Oversoul, then merged with Luna, to create an entity similar in nature and power to the Caretaker.