Main Article: Auriga
Gregorio's ship, the Auriga, has a heavily reinforced bow with spikes, allowing Gregorio to ram enemy vessels when he has an opening.
According to Enrique, who treats and regards him as an uncle figure, Gregorio has been an Admiral since the reign of Enrique's father, whom the game never names or discusses in detail. Enrique was taught all he knew of the art of combat by Gregorio, and the old man certainly went well out of his way to cultivate the image that the prince had of him. Gregorio's weapons of choice were a lance encrusted with yellow moonstones and a spiked shield.
As an Admiral, Gregorio has a strong sense of honor and dignity, something the other Admirals painfully lack. His loyalty to the Empire is to the tenth power, even though he disapproves of the way his immediate superior, Lord Galcian, handles and commands the Armada. Gregorio's tactics center primarily on maintaining a tight defense until the opponent makes a mistake and lends him an opening. It is this tenacity and doggedness for defense that made Gregorio the Armada's best defensive tactician and earned him the nickname "Ironwall" by his peers.
When Enrique escapes from Valua with Vyse and crew aboard the Delphinus, Empress Teodora orders Gregorio to hunt them down and bring Enrique home to "recover", believing Enrique to have been "brainwashed by the Air Pirates." Gregorio cannot bear to fight against the young boy whom he helped raise and come to see as his own son, but ever the loyal Admiral accepts his orders and traces the Delphinus to Esperanza.
In the ensuing battle, Gregorio loses and begs Enrique to return. Enrique refuses, saying that Valua is "headed down a dark path" and that he will not return until the Valuan Armada realizes the errors of its ways. Enrique explains that, by aiding the air pirates, he hopes to redeem the war crimes of Valua but still wishes his people and mother well. Seeing that Enrique is still acting of his own free will, Gregorio accepts his decision and allows the air pirates to leave Esperanza without further conflict. With tears in their eyes, both master and apprentice part.
When Galcian announces his plans to become the most powerful man on Arcadia, Gregorio realizes that Enrique was right and decides to act. Gregorio confronts Galcian when the latter corners Vyse, Aika, Fina, and Enrique as they try to escape Dangral Island, saying that he "will not stand by while [Galcian] destroys the world!" Throwing the four into the exit, Gregorio tells Enrique that the fate of Valua rests in his hands, and in Vyse's, the world. He then turns to face Galcian, ready to sacrifice himself against Galcian so that Enrique and his friends can escape.
- "I am ready to die, Lord Galcian, but I shall die defending my people against a tyrant."
- — Gregorio to Galcian
Gregorio dies fighting, but in making the ultimate sacrifice he succeeds in stalling Galcian long enough to save Enrique's life. His death traumatizes Enrique, to the point where the prince decides to return to Valua to save his people. After his death, his body is returned to Valua intact for burial, in a rare show of respect from Galcian himself.
- "...Send him back to Valua. And make sure his body is well taken care of. It is worth more than your life. Gregorio... you were always the kind to be the last to stay on a sinking ship."
- — Galcian