A doctor that was part of the group sent to Chapaevsk gone rogue. With a crazed fascination for the zombies he attempted to learn where the various nutrients were coming from in order of the zombie to survive. With a lack of uninfected corpses coming into the research centre, Dr. Leviathan decided to set of on his own to test on fresh bodys. Although with the poor planning he put into this adventure in order to avoid suspicion from his peers, he had no research equipment in order to run any coherent tests. He also lacked any sustenance in order to survive. To kill to birds with one stone he decided the best next step forward was to find a start a new diet. He budded it in his notes, the ZRS diet; the Zombie Research Survival diet.
Although he was careful in his methods, Dr. Leviathan's lapse in judgement in this life threating and crazed situation lead to him consuming the infected prion proteins of several bodies. With the start of crazed laughter and tremendous pain from what he could only guess was a sprouting brain tumor, Dr. Leviathan decided it was best to stop the diet immediately and being his new life as a regular survivor with some skill in medicine.
Living with other survivors, he tries his best to keep his tedencies for a midnight snack of human jerky a secret, he makes various puns (hence his referal to himself as "Cannibill") and terrible jokes to explain his caotic laughter. To hide is pain from the growing tumor he hordes painkillers to himself and uses the excuse that he is a doctor and painkillers are the most important thing for his patients to explain away any suspicion he gets from other survivors.
It is important to note that Bill will never kill if it isnt necessary and will rarely even carry a gun as his desire for human meat isnt that strong. He tends to find his meat from already dead bodies he finds on his journey, which he feigns as an autotopsy whenever he is with other survivors.