Dr. Agón is introduced as a researcher trapped in an endless mine cart loop within Diggery Pokery Mine, enduring this confinement for twenty years. Luca's party breaks the cycle, securing his freedom. He joins the group as a non-combatant companion, revealing himself as a Zenithian and using the alias Dr. Agón.

His knowledge becomes vital upon reaching the sunken Zenithian Castle. Through meditation, he accesses past events and deciphers the destruction of the Golden Orb—a critical artifact keeping Zenithia aloft. Luca had possessed this orb as a child before the antagonist Ladja shattered it. Unable to repair the orb, Dr. Agón guides the party to seek fairy artisans for a replacement. When this fails, he devises an alternative: time travel. Luca journeys to his own childhood, swapping the real orb in his younger self’s possession with a fake moments before Ladja destroys it, thus preserving the genuine orb.

Later, after the party retrieves the Dragon Orb from Talon Tower and returns to Zenithia, Zenithian residents express doubt towards Dr. Agón, questioning his unfamiliar presence among them. Presented with the Dragon Orb, he transforms, unveiling his true form as the Zenith Dragon—Zenithia's platinum-scaled sovereign. This metamorphosis restores power diminished since his ancient battle with Estark.

As the Zenith Dragon, he transports Luca's party directly to confront Ladja at Crocodilopolis, enabling their assault on the stronghold. His presence also neutralizes the teleportation abilities of Ladja's forces. Following Nimzo's defeat, he attends the victory celebrations at Gotha in human form, blending into the festivities.