[X] The reason Rionna's reacting the way she is because she thinks this trip is a waste, and that you can't help her. You need to change that. Be as direct as possible. Be careful not to come across as threatening what she's protecting.
-[X] You can't tell her how to act. But whatever it is she's dealing with back home... you can help her, prove to her that you aren't just talk. True Grief Manipulation is extremely flexible, and what you can't do, you've got people for, or can find people for. Unlimited cleansing is a hell of a bargaining chip.
[X] Cut to voting fairly quickly.
[X] Reaction: Disappointment. Tone: Very serious.
-[X] Calm down.
-[X] Offer cleansing and cleanse yourself.
[X] Look Riona in the eyes. Override interruptions.
-[X] Show her Aurora.
--[X] Ask if she sees anything unusual in the Seed.
--[X] Briefly explain your dewitchification experiments.
-[X] When you heard about her from Nadia, you were really happy, because an expert on souls could make a huge difference in making this dream a reality.
-[X] ...but you can't work with her. Not while she continues to enslave souls. You'll try not to judge, but you're not going to condone it.
[X] She came here with the intent of killing another false Grief controller. What does she intend to do now?
-[X] She went out of her way to present herself as a villain who enjoys enslaving others. You don't intend to buy into that provocation, if that's what she was hoping for.
-[X] She is free to stay in Mitakihara as long as she doesn't cause any trouble.
-[X] Your offer remains open, if she changes her mind.
[X] Be on guard for any aggressive moves, and be ready to signal Mami and Homura if it looks like Rionna is going to attack.
[X] NOT TO BE VOCALIZED, PROVIDED AS INFORMATION FOR BRINA: You won't get anything done here unless you can break her existing belief that you can't help her. So, be as direct as possible about this:
-[X] You can help her: you don't know the nature of whatever problem there is surrounding whatever it is back home that she values so much, but you're capable of an awful lot beyond just moving grief around.
--[X] Virtually anything you're not currently capable of, you either have allies who are capable of or you expect to develop the capability for in the near-to-mid term.
[X] Cut to voting fairly quickly.
[x] Goal: Figure out why she thinks you can't help her. You won't get anything done until you can convince her otherwise.
[x] Strategy: Pry. Be blunt and direct. Leave her no technicalities to use to dodge questions; force her to provide details by making sweeping assumptions that she has to refute.
[x] Assert: You can help her. You don't yet have the details about whatever it is she's dealing with back home, but even discounting your friends, allies, and resources, moving grief around is the least of your abilities.
[x] Ask her what she wants. Not what she thinks she needs to do to get what she wants, or what she's done in the past, but the state of the universe that she desires.
[x] Try to cut to voting fairly quickly; don't let the conversation run off on a tangent.
[X] Sigh, relax your visible tension, maybe slump a little bit.
-[X] "You're not very easy to work with."
[X] Explain and demonstrate your power
-[X] Pull grief from your soul gem, float it around, make a few shapes. Perhaps a flute that starts softly playing music?
-[X] Pull a little bit of grief from a grief seed, just to prove its possible
--[X] Explain that floating grief is easy to manage, especially given use of a 4th dimension of space. If the cloud ever gets to be a bit too much you can just shove it down Kyubey's backhole. We can demonstrate this afterwards if she'd like.
[X] After power explanation, move on to explaining your goals.
-[X] Emphasize your desire for magical girls around the world to be able to live normal lives
--[X] Ultimately, you want to break Kyubey's wretched system of grief and suffering, and replace it with something better
---[X] Some enchanted artefact that can absorb grief, or the proliferation of clear seeds or something that'll ensure magical girls can live long and peaceful lives, witches can be slowly but surely removed as a threat, and maybe Kyubey can even still accumulate grief for his anti-entropy efforts.
[X] Now Riona knows what you can do and what your goals are. What's her place going to be in things?
-[X] She can choose to help Sabrina with her powers, with her experience and very different perspective
-[X] She can choose to go home in peace and deal with her own shit for however long it takes for Sabrina to fix things and bring infinite cleansings all the way to Ireland
-[X] She can, for whatever reason, oppose this. Preferably with logical argument rather than sudden hostilities. Maaaybe don't mention this? Let it go unsaid unless she comments.
--[X] Whatever her immediate choices, know that enslaved and possibly suffering shades of the dead won't be tolerated forever. That kind of shit belongs in Kyubey's system, not ours.
[X] If at any point she displays surprise, cut to voting. If she tries to leave, cut to voting.
[X] Be pensive. Body language should be asking a capital-Q Question.
[X] What does she live for?
-[X] It would be easy to make her out as the classic utterly powerful, knowledgeable, and selfish magical girl.
-[X] Except that that requires she have something to be selfish about.
-[X] And whatever that is, it's pretty clearly back home, with the majority of her shades guarding it. Not her city.
[x] Everyone has a goal of some kind, something that keeps them going.
-[x] You already know mine. Yours though I'm not so sure on. I think there's something specific you want to do with my power. Something beyond survival.
-[x] We both want what the other one of us can provide. We don't trust each other enough to cooperate... *yet*. So we'll trade. You help me find out what happens with Dewitching research, and whatever your goal is... so long as it isn't super-villainy, I'll help you with it, and I'll prove to you with actions, not words, that you don't need to rely on those shades forever to accomplish it. You want my power that badly, I'll designate you my insurance policy if you release a few right now. If the research kills me, and you can claim my soul, it's yours.
[X] Find her core goals.
-[X] Ask bluntly.
--[X] Everyone has something that drives them. We exist to break the magical girl system. Some people only cling to life by reflex.
--[X] Why does she choose to live? (Phrasing, very specifically: not "why is she alive". The meaning must clearly refer to what she lives for, and not lean towards implying that we are asking why we shouldn't kill her.)
-[X] She has a motive in targeting Grief movers. And it sounds like she can't relocate to work with you.
-[X] is her drink enchanted with Memories?
[x] You came here looking for a charlatan, a dragon to slay, but we're not your enemy. We help people. Ask Nadia Bennouna, she'll confirm.
-[X] We don't want anyone to witchout either. We can make a world where no one does, ever again.
[X] Her interests are relevant to us because we want to propose a trade. We might work together even if we don't trust each other.
-[X] Rionna helps with Dewitching research and making the world a better place.
--[X] You can promise that it is exactly what it sounds like
[X] You'll help Riona achieve her goals, just like you want for every magical girl. We have reach and power
-[X] First, we want to apprentice on her enforcement tasks. We will show her our morality as action. She can overwatch.
-[X] Help grant her heart's desire? Even if it's just something that doesn't help others, but makes her happier.
---[X] What could we offer, in exchange for no further soul taking while we cooperate?
[x] Please. Help us.
[X] If you could prove to her that you could help her, would she stop? Or at least pause and not take any more souls. She said 'will not and cannot', not that she wanted to.
-[X] Extend some trust. Show her the Clear Seed. Let her examine it, with the clear expectation that you'll get it back.
-[X] Tell her it's your first step towards Dewitching.