As a child, St. John gained his sense of duty from his father, Ian St. John, who was killed by the Overlanders, leading to Geoffrey's strong dislike of humans. St. John is very loyal to the kingdom of King Acorn and Princess Sally as well, whom he and Sonic often fought for affection from. However, many in the Knothole Freedom Fighters consider him arrogant and rude.
After reappearing shortly before Robotnik's death, St. John aided in the return of King Acorn and eventually re-established the King's Secret Service. It was with this team that he recovered Queen Alicia and Prince Elias, Sally's mother and brother respectively. His rivalry with Sonic has cooled and flared over and over again, but the feud over Princess Sally ended when St. John married Hershey Cat. Geoffery St. John and his team took a leave of absence after being infected with microscopic probes by the new Dr. Eggman.