The WOL and Mass Murder

[Enkidoh]

ffxiv is a blend of ffvii reincarnation and normal reincarnation so iirc theres two things that can happen. either a soul is strong enough to remain intact during the cleansing phase and gets reincarnated whole or if its too weak it dissolves and mixes with the lifestream until bits of what remain form something new.

The problem is, the explaination about what the soul really is in the context of FFXIV's lore is... constantly changing and often contradictory, so this is where the confusion is coming from. For the longest time it was mentioned and assumed that the soul was just entirelly aether, that it indeed returns to the Lifestream after physical death and assimilates back into the mass of aether that constitutes it to be "reborn" in a new form at physical birth, (indeed like how the Lifestream works in FFVII)... but Alphinaud's explaination in ShB about the fae changes things.

Namely there is a second inner layer to the soul in addition to the aforementioned outer layer of aether; a seperate 'core' of aether within it, that appears to be what consitutes a person's memories and personality (with the outer aether layer simply life energy), and which seems to live on in the Lifestream, and this is what more or less remains when reincarnated in a new form (this is where the fae come from - due to the First's leaning to Light and thus stasis, there is a tendency for these soul cores on the First to linger and naturally coalesce on the surface in ambient aether into a fae, rather than pass onto the Lifestream and reincarnate normally). This would also explain things like ghosts and spirits as well taking the form of who they were in life as well.

This would explain neatly how memories are erased too, the process of reincarnation would probably partially 'reform' this core to wipe it clean like chalk on a slate, but some lingering fragments may still remain, which is how the Echo is awoken - by drawing out those lingering traces of pre-Sundering life restores it.