William's story begins with his father, Alexander Corvinus, the First True Immortal. Alexander was a Hungarian warlord who lived in the early fifth century. He ascended to power just in time to watch his village ravaged by an unknown plague. Alexander was the only survivor of the plague. His body had adapted to the virus - his body changed it to benefit himself - and through some unknown means consequently made him the first true immortal.
Years later, with his wife Helena, he fathered three children, two of whom inherited the immortal strain in its active form. These two brothers, twin brothers, were Markus and William. Markus was bitten by a bat and became the first vampire and William was bitten by a wolf and became the first Werewolf (or "Lycan").