The lineage of all vampires and werewolves can be traced back to Alexander Corvinus (played by Derek Jacobi), a Hungarian nobleman born at an unspecified point in the fifth century. The patriarch of the Corvinus clan, Corvinus was able to survive a devastating plague that wiped out most of his village thanks to a genetic quirk. The plague caused rapid cell division in its hosts, and Alexander’s immune system fought back by altering the virus. This resulted in his body completely stopping all cell deterioration, giving the Underworld universe its first immortal.
The genetic anomaly was aptly named The Corvinus Strain. Within Alexander it still possessed the ability to mutate, manifested in the gene fusion that occurred in his children. In the sixth century, Alexander’s wife gave birth to three sons. Their son, William, was bitten by a rabid wolf and the strain mutated him into the first werewolf; William’s twin, Marcus, was bitten by a rabid bat, which mutated him into the first vampire. The third son, unnamed, carried the gene recessively and lived as a normal human, passing the strain down through his bloodline.
While vampires retained a large portion of their humanity, early forms of werewolves were unable to return to human form, resulting in an uninhibited growth of savage beasts across their homeland. The steps taken to push back against the growing horde included the recruitment of Viktor (Bill Nighy), who we meet as our primary antagonist in the first film. His introduction into the war would escalate the mayhem and cultivate an entire sub-species of werewolves.
Written by: Looper