He is, in fact, presently minded to demand of Pharasma that protections be set up to make sure this doesn't happen again.  Among the reasons why he would hesitate to simply press a button and destroy only Hell and Asmodeus, if he could come up with a scheme that he was sufficiently convinced would do that on a first try, is that Pharasma might just build a new Hell, and then take Zon-Kuthon out of the vault and put Him in charge of neo-Hell.

The problem from his perspective is not just Creation as it stands being horrible, but that Creation has no rails against becoming even more horrible in the future if he solves the present horribleness.  It may not be a way that people in Golarion are accustomed to thinking, who have so many problems today that need to be solved right now, but dath ilani try to put systems into states where they will knowably not go bad later instead of just being okay right now.

If Creation isn't knowably on a trajectory that takes it permanently out of being a miserable hellhole, it unfortunately seems to him that his utilityfunction strongly suggests smashing the whole place and letting sentient beings exist elsewhere instead, and the present inhabitants likewise having futures that continue mainly elsewhere.

He's not sure why (earlier?) Carissa expects/expected their continuations to be awful.  His model of Outer Gods and Entities is that the ones which don't care about people will mainly not use matter in a way that involves it being people.

Even the Makers of the Magical Continuum, which very likely don't care about people, aren't taking all of the matter and realityfluid in the Magical Continuum and turning it into unhappy people.  Past-Keltham, possibly, got sent to Golarion because it was a particular kind of intervention that was cheaper to buy from the Makers than anything more sensible; he was not put someplace that would hurt him as much as possible.

He doesn't think that Entities with simulating-eyes on Pharasma's Creation, or who trade with the Makers of the Magical Continuum for information from it, that care about the sentients within it at all, would be trying to continue the people there past the end of Pharasma's Creation with a goal of hurting them.  The ones who care about continuations at all, he would hope, are themselves nice; or trading with Entities that are, in the sum of their goals and auction bids, nice.  If that's not so, he's substantially more peeved with whatever hypothetical Entities sent him here to destroy Creation, and also it seems less probable that caring Entities would want that of him in the first place.

That he is sent here, who will deliver an ultimatum to Pharasma to improve living conditions or be destroyed, is some evidence that he wouldn't have been sent here if the expected result of destroying Creation were to isekai everyone here to worse-than-Hell.  Though of course, the Entities that sent him here could be acting deceptive about that, expecting himself, or Pharasma, to be deceived by the apparent evidence of Their actions.

Safeguards against this ever happening again definitely need to exist, but if they can be negotiated without Pharasma, say among the other gods, then that's preferable to making them part of the Pharasma-ultimatum.  If future disasters are sufficiently unlikely then Creation shouldn't be destroyed just because its laws don't prohibit them, after all dath ilan's laws don't prohibit it either.

She's hoping they can negotiate around what 'sufficiently unlikely' means. For one thing, she thinks Pharasma wouldn't, actually, create another Hell and put Zon-Kuthon in charge of it; that would be a change on a scale that hasn't happened and might not even be possible and that would serve the interests of no existing non-Zon-Kuthon gods and not be consistent with what Pharasma is known to care about. Perhaps Iomedae or Erecura can give better estimates of its plausibility, but it'd be good to know how much implausibility is sufficient for Keltham.

Let him be considered an alien wandering by who sees a lot of matter in an unpleasant state, that can with some work be converted to a more pleasant state of nonexistence.  He's already put in some work to destroy the universe, and made some serious sacrifices about that.

Then, after all that work, some other alien steps in and requests his indulgence to instead transform reality into a different end state which that alien likes better than nonexistence.

He's not especially interested in calculating the exact least pleasant most miserable state he considers better than nonexistence, so that other alien can make him an exact minimum offer that gives him a near-zero tiny fraction of the gains from coordination.

If they're going to be revising Creation anyways, how about if Pharasma comes up with a decent offer that doesn't resemble a hellhole so much anymore, and gets something that She herself considers comfortably better than nonexistence, a state that neither of the two of them consider really icky and unpleasant; and everybody lives happily ever after, except for Zon-Kuthon who ought to be turned back into Dou-Bral anyways.

Because that involves him being willing to destroy some universes that don't have Hell and have an incredibly low probability of ever having Hell, and he shouldn't be willing to do that because it's an awful thing to do to people without even Hell as justification?

She can feel herself having to stamp on the impulse to get emotional again, but it's that answer, rather than the original plan, that is why she hates Keltham and wants to preemptively cryopreserve dath ilan, the fact that he is willing to destroy the world if it is offered the end of Hell. It is that which feels to her like a mad monstrous incomprehensible blankness, like murder for its own sake.

The fact that Carissa feels that way might get him to accept an offer of 4, in this Ultimatum Game, but not an offer of 0.01.

If Pharasma says 'well, I can declare that the Lawful authority over Hell is Carissa, and I predict with very high confidence that I won't change who is the Lawful authority over Hell again in the next billion years, but nothing else you want is the kind of thing I really do as an entity', then Keltham should not consider it accepting an offer of 0.01, to bring hope and comfort and healing to every single person in Hell and never have it again and have everyone else in the universe go on with their good and wonderful lives.

And if Pharasma says 'well, well, I can declare that the Lawful authority over Hell is Carissa, and I predict with very high confidence that I won't change who is the Lawful authority over Hell again in the next billion years, and the other things are also things I could do, but I won't, because I don't want to', and Keltham murders every single person in the universe over that - he can't hide behind Hell, if he does that. He wouldn't be doing that because of Hell. He would be killing trillions of people and sending at least some of them to Hell, because some of Greater Reality is bad, because he personally doesn't like the deal he got.

She doesn't have a purer definition of what Evil is than destroying a universe in which trillions of people live and none are in Hell, because you feel that this universe doesn't give you a big enough share of the benefits of it existing.

No matter how high the stakes are, if you're willing to accept tiny shares of gains from trade, you won't get offered any other deals; that logic doesn't change when the stakes go up.

It seems to her that Keltham is not just rejecting the trade Pharasma offers him, of living in her universe, as not worth it to him, which he may totally do if he likes; but is also going around smashing every trade Pharasma has offered every other person, which they ought to have the right to accept or reject on their own, and rejecting all those trades on behalf of all those people.

If putting Carissa in command of Hell is change enough that Golarion, and every other planet in its plane, and every plane in the rest of Creation, can with that much of a boost, see higher technology and greater cooperation spread from star to star, until people here are no longer living squalid lives where half their children end up in the Boneyard, that then indeed would be enough.  That would be a fair chunk of trade-gain; it wouldn't be the minimum quality of life and maximum misery that got him to be almost indifferent toward this reality's destruction.

Similarly, if universal education got to the point where everybody could actually understand the choice made in deciding to leave Creation for Greater Reality, and it was easy for them to skip the afterlife system if they wanted, he would be okay with that.  But that sounds like Civilization rising to great enough heights that it'd be fine regardless; even a mildly below-average dath ilani might have a hard time grasping Greater Reality shit.  It sounds like a stronger demand to make of Pharasma than just cleaning up Creation's regular mess.

Else if putting Carissa in charge of Hell is change enough that Abaddon can be subdued, and the nearby surface layers of the Abyss subdued, once Heaven and Hell are fighting there side-by-side; if cooperation between Heaven and Hell is enough divine agreement that heroes can stride from plane to plane and smash the slave-pits and torture-chambers, until rulers and parliaments learn what worst of human behavior will earn extraplanar missions of disruption -

- then he might be persuadable to consider accepting a world where people live in squalor for a few decades and go to a moderately pleasant afterlife for a few millennia or eons, until Creation reaches its natural endpoint and those people end up somewhere properly transhumanist where they can grow up for real.  So long as they're not in agony.

It would be a poor meaning to Carissa's life, he does think, if Creation could have become something greater and more exalted than that, but he for love of Carissa did abide by her last plea to accept less.  Does she ask of him to accept Creation's stagnation, in preference to its nonexistence, for fear that Pharasma won't be willing to give more?  It seems sad, to him, for Creation has the potential to be so much more than a breeding ground for souls in a handful of moderately pleasurable afterlives.  He's not sure he'll agree, if Carissa's last request of him is that he permit Creation to wallow in mediocrity and never become itself forever, as that pleases Pharasma; not even as her last request.  But she could ask, and perhaps he would accede, and then Pharasma would not be likely to offer any more.

If Keltham's demands of Pharasma are more, and farther outside the domains in which Pharasma is accustomed to functioning such as who she names the lawful ruler of Hell, then it is likelier that the universe will be destroyed and all within it lost.

It is also likelier that there will be good things it will be much harder, perhaps impossible, for Creation to attain.

But it is one thing to destroy a universe because it is bad, because there are those in it who cry out to die and cannot, and another thing entirely to destroy a universe because it is good but there are goods it does not possess; it would be a fine and joyous and great meaning to Carissa's life, if what she does is convince Kelthams not to annihilate any universes that do not have Hell in them, to save all the trillions of people in all of those universes, and then to devote her eternity to building the greatest and best thing that can be built within creation, which will, she thinks, be pretty great.  It doesn't seem sad to her, because Heaven doesn't seem sad to her, and Elysium doesn't seem sad to her, and Nirvana doesn't seem sad to her, and of course if she's in charge she bets she can do even better. What seems sad to her is for all that all those places are or could have been to be lost forever.

She is skeptical, in the end, that Pharasma can change the fundamental nature of everything about creation, in a way that she is not skeptical that Pharasma can change who is in charge of those afterlives that acknowledge Pharasma's authority to decide that. She thinks it's quite unlikely, and that demanding it of Pharasma almost definitely means everything is destroyed forever. Reasoning with trope-logic, she thinks this might be the thing she is here to say to Keltham, the thing all the careful maneuvering was about: not that a universe with Hell in it is worth existing, because she was never going to convince him of that, but that a universe without Hell in it is worth existing.

(Everyone in it can of course be told about Greater Reality, and destroy themselves if they want to take their chances with it. She predicts that they overwhelmingly won't.)

There should have been more mortalborn gods in this world than Irori, if Irori was possible at all, and it is suspicious to him that neither Nex nor Geb tried to attain divinity.

There should have been trade between stars, if the Outer Planes are connected to all of them, if spells like Interplanetary Teleport are a thing.

Golarion should have attained higher technology, earlier, when +6 intelligence headbands are a thing here; the steam engine should not have needed to wait on the shattering of prophecy.

If Pharasma can't directly help mortals, not even by giving Her priests a contraception spell that some other god designed, then so be it.  He hadn't meant to demand impossibilities of Her, if impossibilities they are, as his minimum gain from trade.

But he strongly suspects that there are measures set in place to prevent mortals from rising, to prohibit mortals from developing into gods even if they naturally would, to prohibit trade between stars and planes.

And whether those measures were born of pacts between ancient gods, or laid down by Pharasma, he had meant to demand, whether of Pharasma or of those ancient gods, that mortals be permitted to rise according to whatever fire is in them, and not be pressed down.  He's not, by his own nature, inclined to tolerate a reserve where mortals are kept as livestock and not for their own good either, even if those livestock are just ordinarily miserable rather than in agony.

Oh, Carissa's definitely planning on building Civilization, if any of Golarion survives to build it on, and they can send some 'arks' out for other worlds, if (as looks likely) Golarion doesn't. It's why she was initially prioritizing Golarion in her planning, the part which wasn't about partiality to her homeworld - she thinks that the place where prophecy is broken is the place where they should be most sure they can build Civilization whether Pharasma approves or not.

Thinking something isn't worth destroying the universe to achieve doesn't mean thinking it isn't very important, or worth making many many other costly sacrifices to attain. 

They could go grab some people in Axis and in Heaven and in Elysium and Nirvana and explain Greater Reality to them and see what they think; Carissa predicts that they will largely not consider themselves livestock, and will be generally very happy about their lives and long-term trajectories, and will likely prefer to keep existing, and she will rethink some things if that turns out false. She'd be really surprised if you can't tell people about Greater Reality in the afterlives, even if you can't tell them while they're mortals.

It's not that she doesn't think that everyone who wants to become a god should have the chance to rise that way. She absolutely thinks that. She means her Hell to be a place where everyone becomes the greatest thing that they can be. She just thinks - and she suspects that Keltham, too, if he's studied the question, will think - that a universe where everyone just goes to nice afterlives and it's rare for them to become a god is better than that universe not existing. She also thinks Keltham will think that at least enough of Greater Reality is nasty that he'd be sending some unlucky share of them to Hell so that some others of them could become gods, which is a trade that doesn't seem very Kelthamish.

They can plausibly grab some Lawful Good and Lawful Neutral petitioners who'd definitely abide by a secrecy oath, and tell them about what he suspects might be much better lives and enhancements available in Greater Reality, beyond Pharasma's slum.  He suspects petitioners won't be allowed to offer specific comparison to actual afterlife conditions, when talking to mortals.  But he could ask the petitioners to assume hypothetical Greater Realities and the basic isekai hypothesis and ask them if they'd want to leave (together with their families); and, if so, the maximum tiny fraction of themselves that could end up somewhere worse than Hell before they'd switch decisions back.  They can put that on the experiment list.

But if it turns out that almost nobody gets to be a god, because of Achaekek?  Who he's planning to kill, obviously; but suppose that Pharasma says She's going to run right out and build another Achaekek, or the ancient gods say they'll do that, so mortals don't get too uppity.  Pharasma says that Carissa gets to take charge of Hell, but forbids her from trying to build Civilization, and demands indeed that he destroy Golarion (in an ordinary way, everyone there still gets afterlives) so that nowhere prophecy-breaking can exist where Civilization could ever rise.  What then?

He, of his own accord, would probably tell Pharasma that he's fine dying together with Her in a fire, in this case.

Carissa predicts that probably an overwhelming majority of everyone in Creation would not prefer to be thrown into that fire, and she thinks that maybe this is a case where the dath ilani nature being quite different from the Golarion-nature is important. Most dath ilani would perhaps be miserable if they ran out of all the things to do and read and learn at their current Intelligence and couldn't get smarter faster than they got bored; this is, she thinks, not how most people work. Most people, she thinks though less confidently, don't even want to be gods, they want to go to Heaven and live in peace and comfort, doing meaningful things surrounded by people who love them, and they're not wrong, she thinks, and they won't get bored, she thinks.

Carissae are not like this, actually, not so easily satisfied; and you could imagine that those people are just failing to appreciate the depths of the difference between their lovely perfect life and the better things they could grow into. But - that seems like a different kind of claim about their incapacity to decide their own lives than claiming they don't sanely choose Hell.

The reason Carissa agrees they don't sanely choose Hell is that when they do go to Hell, they regret it.

But if they go to Heaven and don't regret it and don't wish they were gods, it seems like much more of a stretch, to say there's some deep sense in which they should have been enhanced into something that would regret it and want to be a god.

He's not gonna hide it, he is frankly concerned about the process that produces lantern archons like the one he met.  Like, if that was a Boneyard baby who went to Heaven the moment they developed a discernible taste for helping other kids at age four, maybe okay.  If that was a normal Golarion peasant whose trip to heaven involved the equivalent of sudden intelligence-reducing brain surgery - one source claimed that petitioners absorb the material of the plane they're on, and didn't mention carefully developed safety protocols for delicate soul surgery - it's not totally impossible that he decides that Heaven also has to go.

He realizes that Carissa Sevar is probably not happy about this stance, and he hopes Heaven turns out not to be full of horrifying brain surgery that makes people into stupid happy lantern archons that don't remember their past lives.  But that whole lantern archon experience is something that, in retrospect, INT 18 Keltham was a giant flaming idiot for not getting worried over earlier.  Even Cheliax's approved presentation of a lantern archon should have been an enormous flaming warning sign about afterlives.

(Sometimes he feels like he can't understand how dath ilan actually works when everyone there is so stupid that past-Keltham was one of their relatively smarter kids.  He does, in fact, understand, because it's not that complicated in an absolute sense; but on an emotional level, it feels absurd-even-if-true that you could have a functional society where the average Intelligence is only 17.  Their Wisdom in Golarion terms he estimates higher, but he doubts it's over 22-equivalent even in the specialized aspect of cognitive reflectivity.  Even if there's some smarter people around, in retrospect it feels like a society like that should just fall apart.)

Carissa is going to stick to her principled stance that if people like their lives and don't want to die it is extremely wrong to kill them because you think that they shouldn't like their lives.

....it does mean a lot to her, though, that Keltham is considering how far he is willing to move in her direction on this. It is the first thing in a long time she's felt - hopeful and less lonely about. this whole thing. And if it turned out that Keltham and dath ilan aren't willing to destroy any worlds that don't have Hell in them, then she thinks, for whatever it's worth, she wouldn't hate them and wouldn't want to preemptively cryopreserve them and wouldn't regard them as fundamentally basically a Carissa-utility-pessimizer under most circumstances, and she would be very very happy, to change her mind about that.

He appreciates that it's - possible to move Carissa at all, in her feelings.  He was - worried, about that, and maybe he was wrong to ever be worried but he was.

The lantern archon scenario he's worried about is when people going in do not have a good picture in their minds of the soul-surgery they're about to undergo, when they think they're fine with it happening to them; and then they get modified into something that is super happy and cheerful about being a lantern archon.  It's not that he wants to destroy the lantern archon because he thinks it's wrong to be happy to be a lantern archon.  It's that he would want to destroy Heaven before it turned any more people into lantern archons.

....Carissa isn't sure she wants to destroy Heaven about that but she agrees it'd be a really horrifying thing to do to people, among the most horrifying possible things. She would be really surprised and disappointed if the Iomedae was doing that or letting people do that. It seems like the kind of thing where Carmin would say, no, try again and come up with something that isn't horrifying.

That said, the reason it is horrifying is that it's kind of like being murdered, so it doesn't really seem improved by murder.

Iomedae isn't making these putative lantern archons, on the hypothesis he's worried about.  It's how Pharasma built afterlives to work and Iomedae can't do anything about it without Pharasma's permission.  Maybe even Pharasma can't do anything about it, and then Creation might have to go.

To prevent future people from being, possibly, worse-than-murdered, in a way that it's harder and maybe impossible for rescuers Elsewhere in Greater Reality to fix.

Carissa is confident that most petitioners who go to Heaven do not show up there as lantern archons or lantern archon building material.  They show up there as petitioners, and at some point some of them become outsiders, which seems pretty likely to be deliberate and voluntary and in fact the kind of thing Iomedae or the other Good gods could influence; Asmodeus, after all, has a hand in the making of His petitioners into outsiders. She agrees this is worth getting confirmation of.

She is trying very hard not to evaluate Keltham off his willingness to destroy Creation in this particularly unlikely hypothetical, getting mad at him for unlikely hypotheticals in which he'd destroy creation is clearly just disincentivizing him thinking through with her where he actually draws the line. She will just not worry about the unlikely hypothetical where Heaven's process of making outsiders is as involuntary as Hell's.

It certainly is a very Carissa fact about Carissa that she seems, in some sense, more readily to be horrified and admit her horror, 'among the most horrifying possible things' as she puts it, about a hypothetical process that seizes petitioners and turns them into cheerful lantern archons, compared to, say, the process that makes devils.  Perhaps this is an important natural attitude to have within your emotions, for somebody who intends to become the new goddess of Hell -

(A stab of agony that he sets aside; it's not as if he was planning, himself, to survive this event as himself; or as if there was any realistic prospect in the first place of getting Carissa back for himself; or even of her living happily ever after as herself.)

Well, Heaven would be making lantern archons stupider and weaker, and that's an awful thing to do, which Carissa will never do. Hurting people is fine; weakening them is wrong.

(He can have her back. But only if he doesn't do this, and she understands why he's going, instead, to do this.)

...would she truly rather get turned into a lantern archon who'll, after that, almost never remember being Carissa, and stay that way forever?  Than end within Creation, and find herself elsewhere, undetectably-to-herself diminished in her reality, mostly in places that would let her become stronger and more herself and learn greater magic and mathematics?  If those were her only two choices and knowably so?

He can't yet feel it, understand it empathically, this choice to exist in places that feel so much worse; only so that some measuring instrument outside of yourself can say, undetectably to you, that there is more realityfluid in you; only so that the little lantern archon you became forever will be more encounterable to other people.