3000+ queues and Error 2002s make it hard to finish this.
Overall, I greatly enjoyed this expansion's story. A lot of the philosophical ideas I'd been kicking around turned out to be right on the money.
Some specifics.
Fandaniel
Honestly, I found Hermes to be a very relatable antagonist - more so than Emet-Selch and Elidibus, despite those two (especially the former) being put up on a pedestal. He's seemingly the only person who is ever unhappy in the world, and feels he's an aberration because of it. This resonates strongly with those suffering from depression (or any mental illness, really) since they tend to suffer in silence; the PC showing him he's not alone was touching.
He's also the only one who seems to take issue with the others' disregard for living things - the only one who feels life has intrinsic value. Which is, again, relatable.
His decision to let Meteion throw the apocalypse at Etheriys as a twisted interpretation of how the Ancients test their creations? Less so.
Amon is... less interesting, though the pathos he's given at the end almost makes up for it. Reminiscent of Kil'Jaeden from WarCraft - despaired and so did lots of terrible things, but earnestly hopes the protagonists prove him wrong. Unfortunately, dragged off to be broken down by an unrepentant and still Zenos-obsessed Asahi. Following Xande's nihilistic ideals ain't so smart, boyo.
Great antagonist, understandable motivations. Just remember to get past nihilism next time; this is a major step for any philosopher.
Elpis
Ancient Emet-Selch looks like a Xehanort, and it was incredibly distracting the whole time.
The window into the world of the Ancients was otherwise interesting. Got to see more of Emet-Selch's good side, Hythlodaeus is kind of meh, and Venat is nice as a mentor figure. Very beautiful, perfectly managed landscape, and insight into how Amaurotine society operated (exactly like you'd think it would). My one big complaint, in general, is Hermes' Kairos system wiping everyone's memories except yours and Venat's of your time together; felt more than a little like a plot contrivance.
It's probably been mentioned before but like a lot of Amaurotine stuff the name is Greek - Elpis was the spirit of hope, the last thing left in Pandora's Box, and associated with flowers. Elpis flowers are symbols of hope throughout Endwalker, making the name very fitting.
Meteion
She's fine, more of a thematic villain antagonist than a character a la IX's Necron. Fortunately Meteion is given more characterization and much more screen time than Necron, and meeting her in ancient Elpis (before she's crushed by the universe's existential despair) lets you see her good side and make you care about trying to save her.
Endsinger wasn't that hard to beat, and teaming up with frenemy Zenos was awesome. Thankful she seems to have made it back to Etheriys - one of her, anyway.
Zenos
Getting upstaged at the moment of your triumph and then chewed out for your stupid selfishness by Alisae? Makes up for it in a big way by riding to your rescue, even if for his own selfish reasons.
I think Zenos is there partially to temper the message of the game - it constantly presses that you should never stop looking for happiness and purpose in your life, but Zenos proves you aren't guaranteed to find either. He also deconstructs Nietzsche's "ubermensch" idea, showing that someone who lives only by his own ideals without regard for the rest of the world will ultimately end up completely alone because people don't exist in a vacuum. Even then, his (twisted) bond with the PC is what gives his life meaning, though one can't say a life that exists solely to antagonize someone else really has much value.
Ultimately... it's a JRPG, which tend to focus on unity and friendship due to Japanese social standards, so someone who lives and fights only for themselves will be painted as being in the wrong (Re: Persona 4 Arena: Ultimax's Sho Minazuki).
Future Content
Anyone figured out what the mystery we were supposed to see was? I didn't do any sidequests so I might have missed something, but I didn't see any big questions raised here. Some things unresolved (e.g. Zenos' dreams of the Final Days) but nothing new.
So... the guy talking about Pandaemonium at the end is obviously unbroken, pre-Zodiark / post-death Elidibus. I'm curious how things are going to go with that.
Lots of ideas thrown out by Emet-Selch during his brief appearance in Ultima Thule, but it's anyone's game exactly what's next (if any of them). Scions breaking up was bittersweet, but we all knew it was plausible if not probable.
Uh... I was right about a lot of plot points I don't feel like repeating, but suffice to say I enjoyed the story and its philosophical themes. I hope we get more stories like this.