Alright, the introduction of a third etheric 'faction' has given an interesting twist to the situation.
Let's break down what we know.
Fae - Unable to reproduce normally. Born of being Seen into being. Require those easily influenced to See more fae. Likely something approaching parthenogenesis, where dancing fae then 'split' into more dancers. The 'King' of the Fae seems to have no additional powers beyond the ability to dominate the mind of a human. Encourage serfdom if not straight slavery. No real society? Classical treacherous spirits? Appear to be almost pure energy(?) (Feeds on (?), Fed on by Fish People. Seemingly hunted by hounds, but not effectively)
Fish People - Appear to be in the same evolutionary(?) branch as Writhing Tendrils and Serpents. Born of a single human who turned into Writhing Tendrils. Seem to be capable of reproduction(?) which seems to involve serpent eggs(?). The Ocean King is more powerful than other Fish People, but primarily an etheric user. We still are unsure of what one of his techniques actually does. Seem to actually have something of a martial society, with the guards trained in combat to defeat etheric foes. Seems to have no problem with humans, but also no intent to help. (Feeds on Fae, Fed on by (?). No hounds underwater, no similar divergent evolution/too weak to take down the fish folk?)
Parasitic Plant (Audrey) - Seems to reproduce by implanting seeds into flesh. Very not human friendly. Seems to be sufficiently intelligent to be able to communicate, but has been where it is for a long time. Actively Dislikes Midgard. Related to upcoming content. Very vague, complicated by the lack of ability to question it or its spawn. (Feeds on (?),humans, Fed on by (?). No hounds involved?)
This actually seems like a full circle, the fae feed on the flower, stealing nectar and power, the fish people eat the fae to absorb their energy directly, and the plant feeds on the fish people for flesh and fertilizer. Of course, the plant is much more distant than then other two, so this is only theoretical. (Bonus damage for parasitic plants on the fish folk?)
But the primary point for bringing this up, was to murder the plant.
We can destroy the King of Fae. Not fight, but can just make him cease to matter. (Sea water affects the fae? The urn itself? Why are the urns more important than the runed jar? Why can't they make more of the jars?) Can also kill leader of current serfs/slaves. (What keeps them there? Are they protected by the fae? Forced into submission?)
We can defeat the Lord of the Sea. You need to be able to reach him either by force or by request, but you can kill him. (Why are the numbers of guards not refilled? Are they just that hard to train? Is the equipment no longer reproducable?)
The plant, even with the (currently) unexplored Rush It option, is obviously not going to be easy to remove. It's a weed, and it's an aggressive one at that. Of course, looking at the tools we have available, we have a bigdigger. We can dig up the primary root. Likely a lock-out to each path depending on how we decide to gain access to the facility.
It's looking more and more like we should be able to wipe out all the etheric 'factions' to some extent. But in each case there's no real effects. The fae keep flying, likely because that's all most of them care about. The fish folk don't seem to bat an eye at the king being violently dethroned, and the king himself seems mostly disinterested when you try to kill him. So I'm almost curious to see how Audrey responds to a lethal attempt. No worries, since it expects to regrow? All the faceless workers burst open into a flowering plant-zombies? Cannot actually 'succeed' at killing Audrey until you cut out his root, at which point he becomes an improved foe/art image, like the flickering barrier?
How many more factions can there be? Audrey is the closest to tooth and claw nature, but is an insidious invader. (Side effects later involving plant zombies? Bonuses outside the city walls in 'natural' areas?) The fish folk are obviously tied to water, which makes them unable to help/hurt in many situations, but are the most militarily capable thus far. (Side effects … No support in later game?) The fae have almost no structure, but seem to get away with being mostly impervious, highly stealthy, and highly reflexive. (Side effects, more missing children, 'quests' that have no actual reward or need, but also many more fae triggers possible in later game)
Anyway, just a little brain dump on our current state of etheric leaders. Let's see what happens.