Note: Not to be taken seriously unless you've had too much caffeeine like I do.
As of now, Xenosaga doesn't seem to be a part of
the same series like Xenogears is, so these theories were from when it
could have been.
* Kos-Mos-- I think I've figured out her role! She's THE
MOTHER. She does have dual personalities as indicated by two different
sets of eye colors. I believe the first persona (red eyes) was what Kevin
created. The second persona (blue eyes) was what Shion wanted. The only
problem with this theory? She's a frigging robot. XD
* Chaos-- He's definitely NOT normal. He took on a gnosis
(no hilbert effect!) in Xenosaga. Also, there's a very strong evidence
that he's not even human in Xenosaga 2. (Come on, standing on a ship in
space where there's lack of oxygen?)
* Wilhelm-- Well. Most people I've seen are speculating that he's The Devil or something. I'd have to go with this because, erh, God isn't present and I would like to think that God is pretty netural.
* Deus-- Where the hell is that bastard? I know there are several factors that require Deus to be present. We've got gnosis, Kos-Mos, Merkbah, Omega System, and ZOHAR. However, I suspect that Shion may change into a gnosis. (She survived the gnosis attack!)
* Jin/Citan-- Much like how Abel/Kim/Lacan were reincarinated over the years... I'd believe the same thing happened to Jin. It would only explain things about Citan. They both are doctors (Jin stopped because medicine was so advanced that there was nothing that he could do but talk to the patients), soldiers, skilled with swords, able to think clearly and serious, and pretty much pilot the same frigging gear: Hemidall!
* Hemidal and Crescens-- Both gears apparently were mass-produced but they must have at least survived the crash for them to be re-used for Citan and Emeralda.
Xenogears and Xenosaga are copyrighted by their creators.