Inquisitor Mendoza is the leader of the Inquisition, traveling from place to place while warring with the titans that have recently been released. He leads the Order of the Holy Flame on the island of Faranga, where the first Risen game takes place. As the leader of the faction, he wears Inquisitor Armour, but he also has a magical item called the Ocular, which allows him to see (and therefore combat) titans. He is armed with a Double-Bladed Staff, which he uses to devastating effect: even if the Castaway wears full titan armor, a single well-landed blow by Mendoza can do in excess of 260 damage. The Inquisitor plays the biggest part in the game, no matter which faction you choose.
At the start of the game, a cutscene shows Mendoza aboard the same ship as the Castaway and Sara when it is attacked by a large water titan. The Inquisitor attempts to use magic against the enemy, but he is outmatched. Seeing he is unable to prevail, he teleports away, leaving the others on the ship to their fates.
The Nameless Hero doesn't again meet Inquisitor Mendoza until some time later, where the zealot outlines a plan he has for confronting the forces pouring out of the bowels of the island, as well as discovering what power lies within. His hope is that the power can be wielded to defeat the titans.
It is clear that the Inquisitor is in power over the members of both the Inquisition and the Order of the Holy Flame. Many of the Order and Inquisition follow him blindly, such as Ash, Kato, and Ethan; even when Mendoza chooses a dark path, they continue to follow him, betraying alliances without question. Others, such as Commandant Carlos and Master Ignatius, realize that what the Inquisitor proposes is questionable, and they refuse to support the decision.