Returning to the subject of souls and Phoenix Lords...
We know that the Eldar Exarchs (Phoenix Lords are basically superior Exarchs) contain many spirit stones, which means that the wearer of the suit sort of has multiple souls as the same time. In case of the Phoenix Lords, the suit could contain hundreds, if not thousands, of Eldar souls, all of them former wearers of the suit. The first soul however remains dominant, his/her character remains the strongest.
Going back to our "alien" race. I could see the corporations messing with "soul containing" technology, as part of their psionics tech projects. What if during the Psidemic this went to another extreme? Namely the eventual creation of a type of suit that could house many human souls? Those who are psionically powerful enough (in other words those who are powerful enough through enough believers) get to wear the suits since the others are too weak.
These suits become conduits/shelters for thousands, if not millions, of human souls. The wearers are simply controllers whose bodies eventually also die. However, their souls live on and still control the suit (almost in a Terramorph like way).
The idea behind these suits might have been that they are akin to a sort of "Noah's Ark", containing enough human souls to repopulate their colony once things have calmed down. In this way, these suits are very much akin to how an Artiloid could technically create an entire human colony on its own.
Now imagine these "Ark Suits" being found by the Legion or drifting off into newly formed colonies? The suit will try to find host bodies to place the souls in, either building new bodies (through cloning, or mechanical ones akin to golems) or try to take over those who are on that colony (mass possession).
Gives it a totally different twist huh? ;D
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