Quote Originally Posted by Jojoya View Post
What the MSQ didn't clarify is what happens to the cleansed souls once they're used. By being stripped of all memories then imprinted with the memories of the dead person they revive, does that soul become that second person? What if the soul is used solely as a power source for the computer - are they destroyed completely just as the souls of those who became Blasphemies were destroyed?
A soul's aether can be used up like any other power source. Venat spent the last of her soul to fight us as Hydaelyn, and Zenos does it later at the end of Ultima Thule (he openly refers to it as "burning the candle of my life"). In both cases, the implication is that they're deader than dead, with not enough left to return to the aetherial sea and reincarnate. Whether that happens to the souls used up by the Endless is as yet unrevealed, but given that they need to keep taking more rather than relying on their own world's lifestream replenishing itself, it seems likely.