Origin

Shion Uzuki is a scientist, a member of Vector's highest ranking scientists. She worked on KOS-MOS back when Kevin was the head of the KOS-MOS Project. However, she's become the top scientist, or near the top, of Vector. She is now the head of the KOS-MOS project. Due to many black boxes installed into KOS-MOS by Kevin himself, back when he was alive, many things were programmed into KOS-MOS that not even Shion knows about. A couple examples of such would be the X-Buster, a large laser that comes from KOS-MOS' abdomen and absorbs gnosis.

Shion herself isn't quite normal. She came in contact with the Song of Nephilim, a large, black triangle that gives off a song that has the ability to drive Realiens mad. She also has the ability to hear the Song, which is strange because only a few people can hear it (chaos, realiens, the URTVs, and that's about it). It is highly theorized that she is a realien, or if it's possible, part realien (In the sense that a realien was her mother, which would be hard to believe as realiens don't have a use for reproductive organs. They may be built to look human, but on the inside, it's nothing but synthetic blood and tissue as well as an electronic brain). Reasons to support this theory would be that she can sense gnosis to a certain extent, like when her hands glowed bright yellow just like MOMO's did when a whole lot of gnosis appeared, and she can hear the Song of Nephilim, as well as having been able to dodge a bunch of bullets the size of your head that were fired right at her. I'll explain.

On board the Woglinde, when the gnosis attacked, the AGWS were waiting for a gnosis to appear so that they could destroy it. Of course, said gnosis was actually a human (Shion). When they shot at her, the bullets that came out are designed for the purpose of heating things up. In a sense, the explosion that sent the large bullets flying at her head (She didn't move at all, as if the bullets passed through her), even if they missed her head completely, would still create enough heat as it passed by to boil her face and body alive. It's quite strange.

The fact that, when touched by a gnosis, a human turns into a gnosis is also strange. Another fact that supports the "Shion's part realien or is a realien whole" is that she is not only interested in realiens a lot, but was also grabbed by a gnosis and almost was turned into salt (Yes, salt). Gnosis are made entirely of salt. All humans that are touched by a gnosis are turned into salt.

Gnosis

To go into further detail about gnosis, they are strange looking creatures. They were created by the Zohars (Absorbed in and spit back out as gnosis) and by other gnosis (Through contact). Normally, someone who is grabbed by a gnosis is usually held by said gnosis until they turn pure white and dissolve into salt. However, if they manage to escape the gnosis' grasp, they will turn into a gnosis instead. Just like Andrew Cherenkov did. He was touched, almost killed, and turned into a gnosis later on when he started having convulsions and such.

Let the bad times roll on

Apparently, Shion's life has been pretty tough. Becoming an orphan due to the Miltian conflict (Parents killed in the hospital), having to move to Second Miltia, being in bed and waking up to find her mother and father dead on the floor, and of course, when the boot-up incident with the Archetype KOS-MOS occurred. KOS-MOS killed Kevin, who died defending Shion. Shion then destroyed the Archetype by shooting it in the head, blowing up the parts that make it function. Years later, the KOS-MOS project started up with Shion being the head of it. Not only does Shion think of KOS-MOS as the only thing left of Kevin, but she also has second thoughts about her, seeing as when you get in her line of fire, she'll shoot you. For example, Lt. Virgil was shooting at a gnosis when the Woglinde was attacked by them. Lucky him, he was in KOS-MOS line of fire. Out of the two options KOS-MOS had, kill Virgil or don't shoot at Virgil and move away, she figured that killing him would be the better choice (As it had a better chance of surviving it). So, she shoots him with her gun, he dies, she continues to fire, he's limp on the floor, and Shion's in a fit over what KOS-MOS has done.

This teaches us all one VERY valuable lesson: Do not get in KOS-MOS' direct line of fire lest you wish to find your on the floor, darkness overcoming you. In other words, you're dead.