SPOILERS AHEAD
A rather sad headcanon I just thought of (spurned by a comment someone made in one of the... anti-EW's story threads), about the reasons for the
KAIROS system's existence in Elpis - I mean, why the hell did Hermes even have such a thing? What need would he have of a device that wipes your memory? Which got me thinking.
What if he created this memory-wiping system as his way of dealing with the pain he felt whenever a living creation is destroyed - namely, rather than dealing with it or running from it, he takes a third option by merely erasing the emotional pain completely by resetting his memories when it gets too much? It would also give him plausible deniability if his somewhat more shady operations came to light (read: Meteion), which of course is exactly what ended up happening when he activated it on the Amaurot Gang inside Ktisis Hyperboreia. And of course, as we saw, it wasn't really working, the moment he first appeared he seemed to have a 'sad clown' image, putting on a brave face for show but was clearly an emotional train-wreck inside.
Unfortunately KAIROS's reason for existing is never adequetly explained during EW's story and comes across as just a convinent deus ex machina, but this theory does neatly explain why it's there (as it is, the moment it's mentioned Emet immediately got suspicious about it, so it's clear it wasn't entirelly above board).
Of course, there is no proof this is why he created it either way, but just my shower thoughts, but it does actually make a lot of sense.