|“|| You've done well to make it this far. I supposed it's best not to underestimate the resilience of insects.
Sergius XVII, known as the Patriarch, is the leader of the Immigrant Fleet and, ultimately, head of the Ormus organization, both introduced in Xenosaga II, even though Ormus and the Patriarch both worked secretly since a long time, Xenosaga I.II will even introduce the Patriarch in the Xenosaga I's plot part.
The Patriarch intends to retrieve the Zohar, believing Ormus is its rightful keeper. He wishes use it to destroy the Gnosis and wage war against the Federation. At the end of Episode II he briefly attains the Zohar and activates Proto Omega, but he is killed by the testaments. He does not reappear in Episode III.
Little is known about how he became Patriarch, except that he proceeded the Patriarchs Julius XVIII and Sergius XIV. There was possibly a patriarch named Sergius XV or XVI who held power before him. The fact that he took upon the name Sergius in becoming Patriarch could mean his ideology followed that of Sergius XVI. Thus, he may hold the desire to seize their original planet. He exhibits hostility toward the Galaxy Federation, and is not hesitant to start war or use force if needed. At some point in the past, Sergius also knew Dmitri Yuriev, yet disliked him and his vulgarity. Because of this, he saw Albedo as "Yuriev's ghost", as he, too, possesses a vulgar personality.
During the Miltian ConflictEdit
Sergius XVII gave the orders to do the Zohar Experiment using the Cecile and Cathe, even though Margulis seemed to already take his order from the Cardinal Heinlein, and apparently already considering the Patriarch be a fool.
The Patriarch doesn't appear in the game, but does appear in the Xenosaga's I part of Xenosaga I.II, during the U-TIC Organization's attempt to frame the Kukai Foundation for the destruction of the Woglinde. Acting as the representative for the Immigrant Fleet, the Patriarch addresses the Executive Committee on Fifth Jerusalem in the place of the random U-TIC affiliated representative seen in Episode I, his motives being to use the government to acquire not only MOMO but the Foundation's twelve Zohar Emulators as well. It puts the base of his role in Episode II.
The Patriarch appears here as someone manipulator, who is skilled in politics and use whatever is needed to reach his purpose. He seems to be highly respected by anyone in Ormus, at the exception of Margulis who doesn't hesitate to call him an old fool, which even Sellers thinks only Margulis would dare to speak like that, even though both Sellers and Margulis had the same plan. Margulis is still respectful in front of Sergius XVII, but secretly plot for his murder and replacement by the Cardinal Heinleim.
Sergius XVII was obsessed with obtaining the Zohar for the ultimate power that his religion and society preached about, but also to destroy the Gnosis, Ormus being as threatened by them than the Galaxy Federation. He attempted to convinced the Federation that the proof given by Vector Industries through KOS-MOS of the Kukai Foundation's innocence in the destruction of the Woglinde, and so the innocence of the Second Miltia's government were fake, in order to win time and create chaos in the Federation.
Adding to this, he used Ormus and its dummy corporations and contacts, including U-TIC and Albedo to unlock Old Miltia and retrieve the Original Zohar and Proto Omega, which was the ultimate weapon in the known universe. Using the Omega System, he destroyed the Ancient Miltia and threatened to destroy the Federation, the Omega System making look the Gnosis's threat far less dangerous. However, his subordinates, namely Margulis, Sellers, and Heinlein, had other plans: they wanted to take control over Ormus for their own motives. Margulis says then to Sergius XVII that he has only one master, and he understands Heinlein tries to take his place.
When KOS-MOS and the others infiltrated the Omega System, they reached the middle of it where the Patriarch was waiting with Proto Omega. Albedo also appeared, wanting to take the Zohar for himself, and attempted to attack the Patriarch, who summoned Proto Omega. Albedo has been seemingly annihilated by one attack of Proto Omega, even though it'll be showed later that he survived.
After the team do a fight against him, he summons the power of Proto Omega in order destroy them, the team looking apparently powerless in front of the might of Proto Omega charged with the Zohar. But, when the Patriarch summons Proto Omega, the Testaments appear and stop Omega from working, and then kill Sergius XVII. His final words; "I am all power!!!"
However, with the death of the Patriarch, Heinlein became the new leader of Ormus, thus allowing him to unleash his own plot. After this, his role in the game was finished, even though his name was mentioned in Xenosaga III at Old Miltia and some information released in the Database.
Margulis was maybe the person in which the Patriarch trusted the more, with Orgulla and Heinlein, and both Margulis and Heinlein ended up to betray him. The Patriarch apparently respected Margulis, though it was clear that he considered him as a subordinate, but the two of them shared some common point of view.
Apparently, Margulis secretly worked for Heinlein since before the Miltian Accident.
Orgulla worked at Ormus and was apparently high placed in the organization. She was extremely loyal to the Patriarch, and the Patriarch had her in good view, proved by the fact he gave her to command the Ormus space station.
Like Margulis, he is arrogant and uncaring towards the lives of those lost for his goals, he is cold but show respect to those having the same religious view than himself. All others are apparently inferior in his point of view.
He also keep a noble behavior, and until his end will refuse to admit he lost, his last being "I am al--", not finishing his word because of his death."
- In the Japanese version of Episode II, the Patriarch is known as the Pope. The title was changed for the North American release of the game due to religious sensitivity issues.
- His name is not said once in the first game he appears, being referred only as The Patriarch. His name will be revealed for the first time in Xenosaga I.II, then also said in the Database of Xenosaga III.
- His true name is likely not Sergius, like most Pope change their name in accessing to their position, and has never been revealed.
- His character model appears in the Character Viewer of Xenosaga III, though he doesn't appear in the game, only few character who didn't appear in the game got their own character model there.