After The Pocalypse had wiped out much of mankind Gregory and Scott attempted to survive. Although they initially managed to scrape out an existence they were brought close to the point of death when their crops began to fail.
Although things seemed to be going well, several months later they were approached by a number of Vampire Elders who demanded that Gregory farm blood for them. While Gregory initially refused he was, along with Scott, tortured into submission.
Introduced in Trust, Gregory is shown as the owner of what appears to be a safe house, he is also shown to be wielding the device given to him earlier by the vampires, which he uses to deactivate his own machines.
After taking in Bernie and the survivors he treats them to a meal, throughout which he pesters Annika. While Bernie tries to ask him about his weapon he is ignored for the most part, before being outright told to shut up by Gregory. After this outburst Gregory says it'd be best for Bernie and the others to head off for the night.
Once Bernie and the other survivors have gone to sleep Gregory begins to clear up, taking in the machine damaged earlier by Bernie. While he is distracted Scott manages to hide Bernie and the survivors in another room, before informing his father that they've escaped. Upon hearing this Gregory at once sets out to track them down.
Once he returns from his hunting he discovers that Bernie has found his secret room. Upon entering he is wounded by Bernie, who interrogates him, before finally killing him.
Although once believed to have been a modest man, his years working for the vampires appear to have made him insane. While he can be agreeable he appears to have a short temper. Even when being interrogated by Bernie he is for the most part adamant, despite Bernie shooting him several times. On top of this he seems to revel in the idea of hunting Bernie and the other survivors.
On the surface he gets on fairly well with most people and, while overbearing to some extent with Annika most of the survivors seemed to get on with him.
Despite being insane Gregory still seems to have cared greatly for his son. While he treated him quite roughly (fuming at him for the survivors escape) his actions all seem to have been for his and Scott's benefit, so it can be assumed he had some attachment to him.
Although not possessing any noticeable abilities he was in possession of a powerful EMP device, given to him by the vampires, which allowed him to control several machines.