George was a single prisoner among the hundreds kept in captivity in the Colosseum whom the Tenth Doctor met when he was arrested for "borrowing" a horse in 120. His true name was never actually known. George was just a nickname the Doctor thought up when he named the only four prisoners who would talk to him. George was part of the organised revolution the day of execution, but the Doctor saved him from being devoured by beasts and was handed a trident by him. George later used this trident to kill Lucius when he tried to stop them escaping. Lucius' body distracted a panther and allowed him to escape.
He had dubbed the Doctor a "foreigner", assuming him a stranger to Rome, and explained local customs to him, including the order in which the games took place. He had said the wild beast hunt started first. The Doctor expressed rage at how many species would go extinct because of the games, to which the four concluded that he was indeed foreign.
George, at at least one point, had gone to watch the games himself, but never imagined he would end up in them. George was thrown in prison because it was suspected that he poisoned someone when he really didn't. He was a very melancholy person, saying multiple times how no one ever escaped the arena, and how the crowd would howl for their blood. He had given up on the slim chance of ever getting out alive. He felt some regret and disliked the games from this point of view, quite the opposite of Paul, who laughed at the games he had seen, not caring much about his situation. (PROSE: The Stone Rose)