Dr. Hamilton attained his doctorate alongside Peter Jenkins, where they studied virology, though the two were not particularly close. While working as a surgeon at Raccoon General Hospital, Dr. Hamilton was also a member of the charity group, the Raccoon Volunteer Corps. By 1998, Dr. Hamilton and his wife were divorced.
In mid-September 1998, the Raccoon General Hospital experienced an influx of patients suffering a strange disease, later known to be t-Virus infection. Dr. Hamilton may have studied the virus at this point, but when the t-Virus contaminated Raccoon City's drinking water and mutated tens of thousands into Zombies he was taken aback when Jack's Bar was attacked. Not aware at the time, he had also been infected.
Over the next few days he was kept on the move, escaping the various mutants in the city while struggling to understand just what happened. In the early hours of 1 October he hid in a shelter, where he took note of a letter from Dr. Jenkins who, by then, was working as a virologist at Raccoon General. There, he assisted in the production of Daylight, a treatment for t-Virus infection, and used one sample on himself, and kept another to take to the outside world. Dr. Hamilton was connected with university laboratories following the outbreak, and may have been involved in the reproduction of Daylight.
Although George lives in relative luxury due to his highly demanding occupation, he has a naturally active lifestyle, and feels much more relaxed when camping or hiking. It is believed that he sometimes romanticized his profession, which more than likely led to the divorce of his wife. However, judging from the quote, "You're worse than my ex-wife!", it is implied that George's ex-wife did something to cause the divorce.
His special ability is making new medicines from herbs found in the field using his medical kit, which is in his inventory at the start of each scenario.
Often, George is paired up with Cindy Lennox, the blonde waitress in the Outbreak series. This is due to the fact that in one of the possible endings for the first game, George and Cindy are the only "couple" ending to be shown. It could also be noted that the two speak to each other with a kinder disposition when compared to speech with other characters. The main thing they seem to have in common is that they need herbs to put their special abilities to use. In the game, he also has a positive relation value with Kevin Ryman. However, he doesn't have a good relationship with Alyssa Ashcroft, due to her stubbornness and pushiness. He is also a poor match for Yoko Suzuki, as for unknown reasons he dislikes her. However, if Yoko rescues him from near death or carries him in danger status, he'll start following her.
During the Outbreak, George wears a white and yellow plaid shirt with a burgundy-colored vest, charcoal-colored dinner jacket, gray suit pants and brown dress shoes.
George has 2 alternate outfits that are unlockable:
Type B: Outdoor Expert: This costume suggests George has an interest in nature and volunteers his time (hence "Raccoon Volunteer Corps" on the back of his Jacket) in the outdoors in some way.
Type C: Operation X: This outfit is only usable in File #2. A Surgeon outfit complete with a face cover to protect from bacteria and other pathogens. (Doesn't change his infection rate though. It's just cosmetic.) George would have most likely have wore a similar outfit while performing surgeries on patients.