- Regula is known as a man of honor, and his loyalty to Varis zos Galvus is well documented. Though he disdains those who oppose the will of the empire, he is not above making alliances with former enemies if it is for the common good.
- Regula is the son of an influential Garlean family and was a childhood friend of Varis zos Galvus. He supported Varis his entire life and helped him ascend to emperor during the War of Succession.
- The Warrior of Light and Alphinaud Leveilleur arrive in the Sea of Clouds in pursuit of Archbishop Thordan VII. Seeking the key to Azys Lla in the possession of the primal Bismarck, Regula confronts the pair alongside Emperor Varis Zos Galvus. They are forced to withdraw when Lucia comes to their aid in a suit of Magitek Armor.
- When the Warrior of Light's party breaks the barrier to Azys Lla, Regula ambushes them aboard a massive Garlean airship, the Gration. Though Ysayle Dangoulain, in her primal form of Shiva, saves them and damages Regula's dreadnaught, she is slain by an onslaught of fire power. The Gration is forced to remain moored at Azys Lla due to the engines being frozen.
- The Warrior of Light encounters Regula on the surface of Azys Lla near the Garlean outpost at the Gamma Quadrant, and engages him in battle alongside Alphinaud, Y'shtola Rhul, and Estinien Wyrmblood. Regula orders his troops to keep them engaged while he goes on ahead to the Aetherochemical Research Facility where he engages the Warrior of Light once more in battle, but flees upon defeat.
- After the Warrior of Light, Krile , and Unukalhai defeat the primal Sephirot, Regula confronts Unukalhai. Although he rebuffs Unukalhai's condemnation of the empire's attempt to control the primals' power, he leaves without a fight.
- When the wards that Urianger Augurelt created to seal off the Aetherochemical Research Facility are removed, Regula enters the facility with a troop of Garlean soldiers hoping to find the "Genesis Expression", one of the most powerful pieces of Allagan technology. Unbeknownst to him, the wards had been removed by Unukalhai, who had hoped to lure Regula into a trap to kill him. The Warrior of Light, Krile, Y'shtola, Urianger, and Unukalhai follow him in. The Warrior defeats Regula and, cornered by the Scions of the Seventh Dawn, he ridicules their arguments against the empire's activities, but states that dying won't help his emperor's plans and escapes.
- hen the Scions arrive on Azys Lla to defeat Zurvan, the final remaining member of the Warring Triad, Regula approaches them and offers to join them in an alliance. Having decided that the Allagan technology used to bind primals is flawed, and thus unworthy to obtain for his emperor, he now seeks to destroy Zurvan. Together with the Scions he ventures into Containment Bay Z1T9, where his troops are already battling Zurvan's awakened thralls. Regula rushes to protect a vulnerable Unukalhai, but is mortally wounded by Zurvan. With his dying words he implores the Warrior of Light to continue to protect the world from primals, and encourages Unukalhai to use his powers to do the same.
- After Zurvan's defeat Regula's men prepare to bear his body back to Garlemald while the Scions are left to acknowledge that courage and sacrifice exist even among their enemies.