Greg was a friend of Magnus Bane. When they met, Magnus became attracted to him. Since Greg had been married to and intensely in love with his wife, Consuela, the pack's second-in command, Magnus eventually let go of his crush on him. Despite this, the two remained good friends.
In the late 1970s, an increase in serial killers and murderers, such as the Son of Sam, caused even more disarray in New York City. Because of this, it was at first simple to cover up the deaths caused by the out-of-control vampires in the city. The werewolves did not know that the vampires were addicted to cocaine through their victims, so the pack, not wanting the Shadowhunters to be alerted and risk being affected when they decide to intervene, decided to patrol the streets and clubs and monitor the vampires before acting themselves.
When Magnus returned to New York in 1977 from his two-year vacation, Greg spotted him at a diner while doing his patrol early in the morning. He quickly briefed Magnus of the latest in Downworld New York, particularly the issue with the vampires. Magnus decided to tag along, and both soon realized that his designated area was quiet and had no vampire attacks from the previous evening he had to report. When he returned to the pack's headquarters afterwards, he took Magnus with him, hoping he would be able to help them somehow.
When the blackout came, Greg was told that the vampires had attacked Electrica, a new and unopened club, where they preyed on the employees. He went to Magnus' apartment to bring him along. Greg was presumably among the werewolves who, instead of killing the vampires, agreed to guard the Hotel Dumort while the vampires recover from their addiction. It went on for three days, after which the vampires, all dried out of blood and the drugs, were released.
According to Magnus, Greg is an extremely handsome young werewolf with shoulder-length blond hair.
- The Fall of the Hotel Dumort (first and only appearance)