Isaac Foster

An illiterate serial killer in charge of floor B6, the lowest in the building. He despises liars and dishonesty above all else and sees himself as a monster. His favourite weapon is a scythe, which was given to him by Gray. He seems to have unnaturally strong destructive tendencies, going into a frenzy whenever he's allowed to let loose, as was the case with him destroying Eddie's graveyard on floor B4. Due to his tendency to speak his mind and being brutally honest, he swears very frequently.

Ever since he was a child, he sympathized with the villains of slasher films. Due to his strange behavior, his mother's partner attempted to burn him alive, forcing Zack to cover up his burns with bandages for the rest of his life. Soon after, he would be sent into an illegal orphanage, where his apparent insensitivity to death and pain would cause the owners to use him as an errand boy, disposing of other children's corpses and being forced to eat garbage. After escaping the orphanage and killing the owners, filled with a newfound hatred for people who see him as a "tool", he would go on to briefly live together with a blind old man who took him in on a whim - however, following the old man's death at the hands of a mugger, he would go back to living on the streets and killing those unlucky enough to run into him at night.

At some point, Gray would scout him out and get him involved in his project.