"Because the colder Keltham is doing something you want, or otherwise doing something you fear, of course."

"If we do this, Carissa, I say this, out of Keltham's last wishes and because I'm feeling strongly instead of being smart, if we do this, we should do this on a Lawful Evil basis, the same way I deal with Ri-Dul, where you get what you compact for.  I was betrayed by those I trusted in part one of this story, and it sure would rhyme if somebody trusted me and got betrayed by me, in part two, even if there were reasons and even if there'd be, no algorithm, that I should've used to make a different choice, of the choices that I actually saw."

"I should go, get my headband now, I have to be outside the Rope Trick to take it from my Bag of Holding.  I have, said that one thing, that Keltham wanted to say to you, and all the other things, that he wanted to say, like that he loved you, or that he wanted and hoped that you'd end up with a happy ending of your own even if it couldn't be with him, those are all obvious if you know the pattern and it hurts too much to say them anyways."

" - okay.

I love you too."

"You have knelt to, to me, for the, last, time, now, because that, hurts too much, to see -"

The man taps her on the forehead.  "I give yourself back to you.  You own yourself.  Imaginary tag points to Carissa.  Excuse me."

He climbs down the Rope Trick, crying.

(He's gone a bit longer than it would take to just remove a headband from a Bag of Holding.)

Yeah, that figures. 

Maybe if she'd had a better plan, if she'd known about the babies, if she'd already actually fixed everything - if she wasn't mostly still scared of what he might do -

Maybe then it would've gone differently. 

But it didn't.

Somebody climbs back up through the Rope Trick.  Looks just like Keltham, but he's wearing a +6 Intelligence headband and visibly has Owl's Wisdom running.

"All right," he says.  "Let's negotiate.  Are you willing to swear, before I reveal potentially dangerous knowledge to you, that you will not use any knowledge revealed here to you, to act against myself nor my plans, in the sense that whatever you learn from me should not cause you to take actions more damaging to my interests than you'd otherwise have taken?"

She'd have hesitations about this except for how he can just turn her to stone if she's intending to act against his interests; with that, it's not a hard call. "Yes, I'll swear to that."

He holds out a single earring, familiar to Arcane Sight, but larger and less spellsilver-efficient than her own version; a specialized geas.  "This earring compels you to keep bargains and promises you make with me after putting it on, unless I violate my side of the compact.  It prevents you from lying to me, but doesn't prevent concealing information.  It's cursed against voluntary removal, and the geas prevents you from trying to arrange to have it removed.  Once worn it hides itself and looks like an ordinary earring to regular Detect Magic.  I, for my part, swear to you that that's all this earring does."

"Where'd you get that made?" She could make it in a month, probably, but she's actually wildly envious of any other item enchanter who could without having her previous work on the geas earrings to go off. ....well, they could've had more than a month, with the time-dilated demiplane.

"Lawful Evil 7th-circle.  She wasn't starting from scratch, I was able to buy some cursed geas items with more unfortunate specializations and had her repurpose those."

"I want to meet her. I'm putting on the earring but mostly only because you could make me."

"She did not want to meet anyone else or have it known that she was dealing with me."

"You have the option of not putting on the earring and not getting to negotiate with me.  Most of what I want from you is voluntary activity that cannot optimally be forced from you by geas."

"Yes, but this is still not an offer I'd take from someone who couldn't make me. Can you if you deal with her again at least show her something impressive I made and give her my contact information."

"Yes, though I don't have any Sevar items about me besides your glibness pin."

"Once you've put on the earring, repeat your promise not to use knowledge that you learned from me to harm my interests, relative to what you would've done without that knowledge, as is a condition of this negotiation."

She puts it on. She repeats the promise.

"All right.  Diamonds turned out to be tetrahedral Element-6 crystals, for which I happened to know a straightforward, purely chemical synthesis method.  That synthesis is presently in progress in a temporary demiplane I set up to have the environmental conditions for synthesizing diamond, with a scattering of diamond dust within to act as seed crystals.  I expect the diamonds growing there to be large enough for Wishes in about a week.  It's not a large demiplane, though, so I'm not expecting to get more than a couple of million Wish diamonds that way."

"Ri-Dul does not know this important fact, nor does the priestess of Sarenrae below us, and it would be damaging to my interests for you to tell them, or, indeed, anyone I have not told you is cleared for it."

 "- well in that case I think we're actually going to be completely fine. I'd be annoyed I sold my soul for something we can make by the million but actually I can't even be annoyed right now, it's impossible. - I want to know the chemical process for diamond synthesis but that's not even arguably a priority."

"That's a week of realtime, two weeks of demiplane time, and those two weeks may matter considerably.  In particular, they matter for whether or not I have an incentive to destroy Egorian or all of Cheliax to prevent the ensoulment of my children, or as many of those children as possible, or if I'm able to advance other plans to a point where it's clear that Golarion and Cheliax will end up being an acceptable place for children."

"I'd like to buy your Wishes to enhance my Intelligence, Wisdom, and Splendour.  I want to rent your artifact headband for at least a month of realtime.  I will not offer you thousands of Wish diamonds in exchange, because I don't want them proliferating all over Golarion just yet.  I will offer that you may go on the trip to the City of Brass that I was previously planning to take with Ri-Dul, where, I've read, many Efreeti can readily cast Wish given a large enough diamond for it.  I'll send with the Wish diamonds and other payments for you to buy +5s to all six of your abilitystats in the City of Brass.  In the event that I cannot fulfill my side of the bargain in a timely fashion, because the diamond synthesis method failed to scale to Wish diamond size, I will endeavor to pay you back the reasonable value of fifteen Wishes and the headband rental whenever I can.  Unless I am dead and unresurrectable for any number of reasons, in which case you get an unremunerated bad outcome."

"I am sure you realize that's a deal I'd happily make Keltham and would be a fucking moron to accept from Dispater."