Shattered World Crisis
During the Shattered World Crisis, Gregorios was assaulted by Metal Sonic, who had determined that the old man had some connection to the Gaia Temples. Fortunately for Gregorios, Dr. Eggman chose that moment to contact Metal Sonic and dispatch him to Casino Park, sparing Gregorios any further harm. Gregorios determined from this experience that it was necessary to "break tradition" and "warn the others," indicating that he was not alone in possessing knowledge sought by Metal and Eggman. He subsequently contacted the Knothole Freedom Fighters aboard the Sky Patrol to inform them of a means by which they could defeat Dark Gaia. (StH: #268, #271)
Gregorios greeted Sonic the Hedgehog, Antoine D'Coolette, and Chip upon their arrival at the town temple, where he escorted them to a secret door behind a tapestry; leading to the Gaia Gate. There he proceeded to give them a basic rundown of the hidden temples' connected inner-workings and the need of the Sun and Moon Keys in order to enter them. Fearing that the information would eventually leak, he presented them with a list of the locations which the various families possessing the keys resided. (StH: #272)
- Gregorios was first introduced in the game Sonic Unleashed.