The way that pain and loss at times leads ex-Iomedaens to try to destroy Creation, is that they start thinking that, if you turn from Good to Evil, from Law to Chaos, if you throw away all your scruples, so great and dramatic a sacrifice must negate everything common sense says about why that plan wouldn't turn out well in real life. It has to work, if you sacrifice enough; if you do something as dramatic as throwing away your Goodness or your Law, reality has to see your pain and determination and be moved somehow; it has to be worth something, after you paid so much. Mortals sometimes think like that, when they break with Her.

The Keltham that She saw in vision would not break in that direction. The Keltham that She saw, if he had devised some standard mad wizard-scheme scheme to end Creation, would pause and ask himself "Why is Creation still here if it's that easy?", and do more research first. Even if he couldn't rule out every slivered chance at success, he wouldn't chase futilely after tiny chances. Taking into account that later-Keltham made gift to her Church, the Iomedae-splinter strongly estimates that later-Keltham would ask "If all the people like me joined forces with the Church of Iomedae instead and accumulated our efforts over the years, instead of dying futilely and individually in the pursuit of some tiny chance of destroying Creation, would this in realistic expectation lead to a better outcome?" and notice that the answer was "yes". Obstacles to asking yourself questions like that are also obstacles toward donating vast wealth-power-potency to the Church of Iomedae.

The Keltham that She saw, even if he decided that he preferred that Creation not exist, would only try to destroy Creation if he thought he could actually pull that off.

The splinter of Iomedae has cached that destroying Creation is difficult, and has cached that even mad-wizard negative utilitarians know it's difficult if they're thinking at all clearly.

The present time in Golarion is unique, among planets, for that Golarion contains Rovagug and that prophecy about it is shattered. But the splinter of Iomedae concerning Herself with these matters puts very low probability that Keltham would try to unleash Rovagug. Losing the one planet where prophecy doesn't function, and where conditions have conspired to enable an unusual number of mortal-descended gods, would be unfathomably costly to Good, and to the inferred interests of Keltham. It wouldn't work to destroy Creation, unless Asmodeus or some equally powerful coalition backed Rovagug...

...and the Keltham that She saw would not accept partially destroying Creation, if he went down that road.  A partial destruction that leaves large sections of Creation and Hell intact, would not be victory; and that is something the Keltham she saw would not lose track of, not for any amount of desperation.  If he commits to a drastic action he will estimate that actual victory lies at the end of it, and his desperation and sacrifice will not have figured into that estimation process as positive factors.  His deontology is not for sale at the price point of failure.

So, even conditioning on the line of possibility where Keltham would prefer to destroy Creation, the most likely outcome in the Iomedae-fragment's current evaluation of that broad class of possibilities is this:

That if Keltham decided that he preferred Creation gone, Keltham then retreated to his fortress while he looked for ways to destroy all of Creation, ways that would actually work in real life; and so far, Keltham correctly assesses that he hasn't found any pathways like that; and when he finishes out that due diligence, he'll join with the Iomedans on fixing Creation instead of destroying it; and be less at war within himself, and be happier.

A generalization of this scenario is in fact the Iomedae-splinter's primary guess: Keltham has retreated to his fortress - after making sure Osirion was boosted enough to prevent Cheliax from taking over Golarion immediately - in order to properly verify all he's been told is happening, and orient to Golarion, and do something like due diligence on literally everything; and until that's done, Keltham isn't trusting anything whatsoever this time, and doesn't want any gods able to mess with him in any way.

To the Iomedae-splinter's way of thinking, this would be an incredibly reasonable thing to do. The boy She glimpsed in Osirion could easily be one Owl's Wisdom or Fox's Cunning away from thinking it. Iomedae-the-mortal spent years investigating Aroden before committing herself completely to His service.

The true and Greater Iomedae would have guessed better. It is not actually a puzzle that would stump a god coalesced.

Had Iomedae seen Keltham in vision, before coalescing into Her full self, that added knowledge during Her coalescence would have been enough for Her full self to figure out everything - for the exponential thicket of possibilities to collapse and one possibility to stand out - not just Keltham's psychology, but the existence of an alien web of not-prophecy surrounding him.

Even the earlier moment (of which She also caught sight, there having been no effort or oath to conceal it from Her) where Keltham tried to work out Wish-wordings with one of Her clerics for destroying all of Cheliax, would have been enough for Greater Iomedae to consider explicitly whether Keltham held other and greater destructive secrets, knew truths that should be permitted only to Pharasma and Otolmens.

Gods are able deducers, but not superb observers of the Material; many truths of physics are gated behind microscopic observations that no mortal has yet devised instruments to capture.  So gods would not know those truths automatically, without an effort; and being visibly the sort of god who makes that effort might get Them killed.

(Some fragments of Nethys have come to know, and the rest of Nethys dissipated much of His power and sanity on restraining those.)

So then for Iomedae's splinter, the guess that Keltham might possess truly deadly knowledge is not something that would follow from his being observed to improve spellsilver refining. It is not a usual element of a cached pattern. Nothing about Keltham's arrival and subsequent events, seen only from the Iomedae-splinter's angle, suggests this situation could have an unprecedented impact upon all Creation. It is not transparent to Her, not much suggested by those events, that Keltham's arrival in Golarion constitutes rolling a new kind of dice that have never been rolled in Creation ever before.

...also you'd expect that Otolmens would notice, and destroy in body and soul, any mortal working out detailed mathematics for how to destroy Creation; that Otolmens's own veil wouldn't block Her own sight; that She was more than powerful enough to peer through a Mind Blank. Iomedae's splinter doesn't know that any such mathematical insight is possible; but Her cache-hit on that general class of internal question is that, if it were possible for a mortal to destroy all of Creation just by being very clever, it would be Otolmens's domain to notice the mortal in the process of being that clever and squash them.

Her greater self might have spotted the flaw in that cached answer with respect to Keltham, but her lesser self has not. From the perspective of the greater self which laid down those cached answers, that violation would come at the end of improbability layered on improbability, inside an exponentially vast space of other improbabilities that aren't any less probable than that.

...and so Iomedae has not coalesced again.

Her previous ten minutes of coalescence were vastly expensive to Her interests, and not only in Golarion. Iomedae's will and Her care was temporarily withdrawn from many places, more worlds than a young god should really be trying to help; there are countries, small ones, on little planets that don't amount to much, which now stand in danger of falling to Evil as the price of those ten minutes of real thinking. There's a reason She hadn't done it in a century. Greater Iomedae updated many of Her policies, in those expensive ten minutes, not just Keltham-related ones. So the expected utility of pulling Herself together again, so soon after, is much less.

And so Iomedae's decision, to not pay the costs to think really hard about the question - as understandable, as predictable as that decision may be - is the only decision that ends up -

New update!  Iomedae's most powerful followers are praying to Her, asking if She wants to commend them to any particular path about... you know... this entire Cheliax thing.

Should they be, like... backing Carissa Sevar, here, so she can become a new Lawful Evil god of a less awful section of Hell.  Or should they be negotiating in good faith with the new Cheliax, which has voluntarily proposed a regularly updated reassessment of Worldwound contributions that will automatically take into account Cheliax's newfound wealth of spellsilver?  Or should Good be backing factions from out of the old Cheliax, in order to foment internal strife and stop Carissa Sevar from conquering all the parts of Golarion that don't negotiate treaties with her?

They know Iomedae almost certainly can't afford to answer them, but, nonetheless, they have so many questions.

Her second reaction:

Iomedae is not as encouraged as a mortal might be, by how Cheliax is potentially positioning itself for positive changes, or at the stay order on Maledictions. It looks overtly Good, better than the mortals realize, probably better than Hell's local emissaries realize; but minds at Carissa Sevar's Intelligence level can play effective games of deception against gods. Past a certain threshold level of intellect, the masquerade is just correct and even a substantially smarter mind can't pierce through it.

And that leaves you with your priors. It's not lost on Iomedae that Carissa Sevar would be a probable improvement as a new Lawful Evil god, but Iomedae cannot see a plausible pathway for Carissa Sevar to fulfill her cult's announcements and promises.

The Church of Iomedae will be instructed to treat Carissa Sevar as no more trustworthy than Asmodeus, and to relax no vigilance against Cheliax, unless and until Lawful oaths about shared purposes and straightforward coordination are offered them. If Carissa Sevar wants to work with Good on anything she can say so to Good directly, INT 29 should really be enough to figure that out.

...even a fragment of Iomedae splintered, however, will not fail to notice that She is incredibly confused about how this Cheliax situation could have developed out of the Keltham situation. That trajectory is not a short sentence in the language of paladins, probably not in anyone's language. This is not how probability is supposed to work.

Her first reaction: WHAT.

Okay, but is Iomedae about to coalesce?  How close is She to deciding to coalesce?  Even if She doesn't do it now, if She was nearly on the verge of it here, this won't be the last startling news that She gets -

...

Nethys says "Pretty butterflies?"

(Nethys did not expect to have to hold Himself together this long, did not expect He'd have to hazard His mental stamina for so long a march.  Some element of the web of Nethys-fragments meant to spy on Iomedae's thoughts and convey those legibly to the Alliance has lost focus.)

Aspexia Rugatonn is permitting herself to stay awake too long in her vast bed of Asmodean grandeur, thinking about how much she doesn't like all this, instead of just ordering her own mind sharply to behave.  She also has an instinct that it will be dangerous to order her own mind to stop thinking about this.

She really doesn't like the moratorium on Maledictions.

Aspexia sees the rationalization.  She sees the excuse.  Pushing Cheliax in the direction of some cheap Goodness will assist in the spread of Sevar's legend and cult and her eventual ascension.  Which, yes, serves Sevar more than Hell, but Sevar no longer lawfully answers to Rugatonn about that; only Dispater can bid her otherwise...

Swearing off Maledictions is undeniably an efficient way of producing a public shift in the perception of Cheliax under the Sevarian Empire.  It gets them to maybe consider that Cheliax might be starting over, that Carissa Sevar is on their side, to want that to be true.  It lets people hope...

Just like Aspexia Rugatonn is being allowed to hope, herself, that their hope is a lie.

And Aspexia Rugatonn realizes, then, why she is afraid.

If Aspexia's wavering grasp of 'tropes' is at all correct, then neither of those obvious hopes can be realized in the form that they are hoped.  Not Aspexia's own hope that Sevar remains aligned to Hell's interests, nor the hopes of Good people everywhere in Golarion that Sevar has brought Cheliax's Evil to heel.

So the hope can't be real, nor can it be a lie, either one.

And that's a contradiction.

Which means that the whole appearance of Carissa Sevar playing a game for her overlordship and divinity, serving or betraying Hell to that end, with Cheliax as her playing-piece...

"This is also not reality," Aspexia Rugatonn murmurs to herself.  And even as she says it, she knows deep down that this is so.

But she is not an ilani, and she does not know what to do after she says that.

The part that isn't real is, in its own way, very straightforward; and the mask over it is being done correctly, such that the only way to guess it would be on pure priors.

If you looked at that complicated situation developing around Cheliax and trusted your lying eyes, you would get the impression that Carissa Sevar was playing a close and clever and complicated game, concealing her real intentions from at least your side and possibly all the sides, setting in motion some very long-term strategies - strategies spanning a timescale of months, maybe even years.

You would think you had that much time to think, that much time to plan.

Anyone who made that mistake and took their leisure would have no chance to act at all before the endgame began.

And then, it begins.