Before Xenosaga Episode I had even been released in Japan, someone from MonolithSoft's staff posted spoilers on a Japanese Xeno forum. They were translated into English by someone and fans started to argue whether or not they were real or fake, and some people based their theories on them. This leaked information included the following list of information. Most of it would turn out to be pretty accurate while bits were completely off (and may have been speculation on the part of the MSI employee or the result of changes done to the script for future episodes.)
1. Heinlein is head of the religious Ormus association, looking for Lost Jerusalem and the body of Jesus Christ.
2. Febronia is a Realian. The mother of Cecily and Cathe, she was used as a test case during U-TIC’s Zohar Control Project. Sent early in the project to the planet Miltia and subjected to numerous experiments, she met a battle-wounded Virgil one day and slowly fell in love for a short time after repeated meetings with the human. Slaughtered by a fellow Realian when the Miltian war intensified.
3. The original KOSMOS prototype was the same as Chaos a long long time ago, existing as wave beings (maybe similar to the wave existence?). It was later stolen by Wilhelm for his own personal plans. Chaos is hoping to turn KOSMOS back into her original form (it is possible that Chaos is, in fact, a part of U-DO itself).
4. Jr appears to be about 12 years old, but has actually just passed his 26th birthday. Same age as Albedo and Gaignun Kookai. He believes and trusts Chaos completely, and thinks of him as a close friend or brother.
One of the remaining U.R.T.V.s (U-DO Retro Virus), a special set of people "created" as a counter to a set of chaotic space waves known as the U-DO. These waves caused the Stellar Federation to fall into a serious crisis many years ago. During the final anti-U-DO operations (14 years before the story begins), Jr. had to face off against Albedo, a close friend who suddently went berserk. Dealing with him required Jr. to use all of his abilities to their utmost limits, consuming the majority of his life expectancy in the process. As a result, he has suspended the growth of his body indefinitely. Using his ability to control synchronicity (the coincidental occurrence of events that seem related but cannot be explained by pure logic), he has a measure of innate telepathic and telekinetic ability. As a result, the world has placed him squarely in the position of a psychic (which is indeed what most of the Gaignun family is composed of).
He is portrayed in the story as an impulsive, reckless, pure-minded boy. A lover of women by nature, the only flaw in his personality is the way he uses his innocent looks to make girls fawn over him. On the other hand, his attitude towards other men is caustic and he has no trouble bluntly saying whatever he wants to them. Despite the light air that surrounds him, he has wide knowledge about the world, and he occasionally acts more his age and makes bold statements that cut right into the heart of matters. Enjoys collecting old (for this time period) books and guns.
5. U-DO is a conscious existence, evolved from an artificial brain life form created as a navigational device for the U.M.N. Its internal systems were the basis for the Realian project. Claimed by U-TIC during the Miltian Conflict for use as a control device for Zohar, a mutation machine, but went berserk, releasing the Gnosis in the process.
The cause behind what U-DO did was officially described by higher-ups in the Stellar Federation as a program gone out of control, but the real reason was a new existence borne into this universe by the opening of a path to a higher dimension. U-DO is looking for the half of its body that was taken from it by this existence. Having existed for so long as a single brain, separated from the outside, it is not clearly aware of itself or the rest of the world.
6. Virgil is the lieutenant of the Marines division. The war twelve years ago that came to be known at the Miltian Conflict took the life of Febronia, his dearly beloved, and since then he has held a deep-seated hatred for Realians. He is killed in the first episode by KOS-MOS, but appears on occasion in spirit form later as part of Wilhelm's Vanguard Force. A man with a treacherous face, DME poisoning (an illness caused by injecting Realian body tissue into the bloodstream) has given him cracked, scarred skin all over his body (note: DME is also mentioned in the UMN Database).
7. Joachim Mizrahi is a genius of rare caliber. Constructor of the Hilbert theory and developer of D.S.S.S. Joined Project Zohar after his research caught the eye of Wilhelm. Soon realizing the danger behind the project, he quit the research group after the death of his daughter, Sakura. Retired from public life and secluded in his Mizrahi Brain Physics Laboratory, his own lab on the planet Miltia. After receiving contacts from the secret society Ormus, founded the U-TIC organization. Returned to Zohar research afterward, creating the M.O.M.O. Realien series in the process. Joachim's goal is to find a way to meet his deceased daughter again - to create a road to heaven. He is the only person who has discovered the link between Zohar and the intrinsic structure of the universe, but eventually ends up attracting the Gnosis to the human race.
8. Jan Sauer, otherwise known as Ziggy, is basically anime Robocop. He was an anti-terrorist cop with a wife and son, then he died, got turned into Robocop by Ziggurat Industries, his wife and son were killed in an 'accident'. The "Tensegrity Project" is the Warp Drive project 200 years ago that created Testament and killed Jan's family.
9. Testament (the red-cloaked guy) is the leader of Wilhelm's "Vanguard Force", which Virgil is also part of.
10. Chaos is essentially a nonsensical character based on the Buddhism doctrine:
"A boy who plays a major part in the Xenosaga story. A delicate boy with a look of anxiety eternally etched on his face. He speaks with a calm, clear, somewhat philosophical voice. Although seemingly around 16 years old, his true age is unknown. His main characteristics are his deep, clear amber eyes and silver hair.
He has never told anyone anything about himself except his name, so the path that led him to where he is today, and indeed whether he has any memory of his past at all, is a complete mystery. His existence is similar to that of a ghost of apparition; he causes great things to happen unconsciously simply by being there. He exists because he is acknowledged by others as being there-a way of life he is trying to find a way of dealing with. chaos possesses absolute power, but knowing the history of the ages as he does, he feels a kind of fear of power-especially the power of words-and he never uses it to strive for his own desires. Instead he believes that the future of the universe must lie in people who live the way Shion does, with the will to live, the will to advance, and most of all a sense of self-awareness. He has no qualms with helping such people.
Since he is knowledgeable of everything in the universe, he will be portrayed throughout the story as a bright, well-mannered young man that always looks at the current situation from a removed perspective. His name means 'chaos'. "
11. In AD 2000, Wilhelm formed the foundation of Vector Industries, which has owned the technology from then till Episode I. He believes in the "Der Wille zur Macht" in each human being and wants to use all this power to save the human race from a "great horrible future" that he envisions.
12. Sellers (the pink-haired guy with shades, seen talking with Margulis in Episode I) is a scientist in the Ormus association. A colleague and fierce rival of Joachim, he plagiarizes the results of his research after his death. Sellers is being guided in the background by business or political interests, but apparently this area won't be explored in the Xenosaga series of games.
13. Allen is the vice project head of the KOS-MOS Project, Vector Development Team No. 1. Holds some feelings for Shion, his boss, but rarely brings these feelings to the forefront. The accident that took the life of Kevin, Shion's former lover, and the inferiority complex Allen held against him, are still too fresh in his mind. A simple and honest young man who speaks freely and easily.
14. Nephilim is a mysterious girl that appears now and then in front of Shion. Exists only in spirit, not in body. Trying to save both the Gnosis and the Realians. Grows into an adult by Episode 2. It is possible that she is the Original Elehayym.
15. Jin Uzuki is listed as a playable character . His background is similar to that of Citan Uzuki's. His rivalry with Margulis arises partly due to the inheritance of his sword. Margulis, according to the Xenosaga OST linear notes, seems to portay "the modern working world" (whatever that might mean).
16. Kadmoni is an emminent Zohar Control Project, which is capable of creating Realians (it is believed that U-DO was also involved in this as well). There seems to be an intrinsic relation to Kadmoni and Realians with the people of Xenogears, as well as Realians living on a far off planet in peace and harmony as 'true humans' (again, might be referring to the planet of Xenogears).
17. Raziel is an electronic brain used to navigate super-sized warships.
18. KOS-MOS androids are autonomous emulations of "Mary Magdalene".
19. The original KOSMOS prototype was the same as Chaos a long long time ago, existing as wave beings (similar to the wave existence). It was later stolen by Wilhelm for his own personal plans. Chaos is hoping to turn KOSMOS back into her original form (it is possible that Chaos is, in fact, a part of U-DO itself).
20. It is possible that the 3rd Rhine Maiden is the Eldridge.
21. Time before time:
The Ormus looked after the Zohar, and Heinlein, Wilhelm, chaos, Abel, and Nephilim were all people from this time. And Heinlein, because of his private urges, went against Wilhelm, while chaos remained neutral even though Wilhelm asked him to help. And in the 21st century, Heinlein and Wilhelm interfered the world with Hyams and Vector. But the Zohar went berserk. Heinlein left earth with the emigration ship Pleroma, this group became the Emigrant Convoy,while Wilhelm went with the other ship, which became the star federation.