It's a bright spring day in Ponyville, and Twilight Sparkle is exactly where you'd expect her to be. In the library, that is. Specifically, she's hunting for where she mislaid Principles of Proto-Equestrian Orthography because she just can't read Starswirl's hornwriting without it. Hmm, maybe Spike put it back in the storage room—
Milliways is an interdimensional bar accessible from a large number of different universes. Time in a given universe does not pass while a patron therefrom is inside with the door closed. Food, beverages, and books from any of the universes from which Milliways is accessible are available for purchase. I can accept almost anything of value in exchange for purchases but you do have to pay somehow.
Violence against other patrons is strictly forbidden in the main bar area. Security will be enforced by categorically adequate means.
Brown isn't that exotic a color! Dr. Whooves is brown—that said, she's not entirely sure that Dr. Whooves isn't himself an alien. Mostly, her reaction is 'aaah why is she so big' and 'what happened to her face'.
Katixa will see a pastel purple winged unicorn about three feet high at the shoulder, reading a book and drinking from a teacup that she's levitating in front of her face. Compared to the animal that some other places call a 'horse', she has a much larger cranium and shorter snout, with large, relatively forward-facing eyes. Her mane and tail are multicolored and there's a design apparently dyed into both of her flanks.
"Oh, hi!" she says to the new arrival, suddenly looking up from her book. "I'm Twilight Sparkle, Princess of Friendship. What's your name?"
(The Equestrian language actually consists mostly of phonemes that Katixa could in theory produce, but it's not familiar to her, and if the translation effect is causing her to hear, say, Taldane, then she may not realize that she can reply.)
... oh, right, the alien doesn't speak Equestrian. Why would she? Still, one wonders how the bar does, so it's worth testing. "Tap your hoof twice if you can understand me but not reply," she says.
She offers Katixa the teacup. It's full of tea, though probably too small for her to drink from without spilling the entire thing.
"Um, anyway, this place is called Milliways and apparently it connects to a large number of different universes," she tells Katixa. "The bar is intelligent and you can ask it for things; it says that in here, you can talk if you try. There's translation magic active, or else you wouldn't be able to understand me."
"I'm glad there's no fighting! I'm technically a Princess but I haven't been one very long and the older Princesses do most of the actual governing. I suppose that talking to aliens probably would be one of my royal duties, although I found this place quite by accident and didn't intend to meet any aliens when I woke up this morning." It's probably not in Celestia's power to create an interdimensional bar but she absolutely would arrange the whole thing just as it's happened if it were.
"Uh, what's your name, by the way?"
"I'm Twilight, but I think you already know that. It's nice to meet you!"
"Tell me more about your world! I've only been to one alternate universe so far but it didn't have any ponies* in it."
(*) From Twilight's perspective, Katixa is a very weird-looking pony, but a pony nonetheless.
"Uuuuum, I've only been a person for about a year and a half so I don't know all that much even though my paladin tells me stuff all the time. But it's got evil gods! One of them had a whole country! We have been working so hard to help the country not be the kind of country that an evil god made it be any more now that we have won it from the forces of Hell!"
The words 'god' and 'Hell' don't translate precisely but that still sounds. Uh. Yikes.
... she should, probably, like. Tell the Princess that Equestria has made contact with a universe that has evil gods in it?
"What do you mean, you've only been a person for a year and a half?" she asks Katixa. (Presumably if she were only that old she would have just said that.) "—hold on, I probably ought to tell some people from my world what's going on." And she trots over to the door, pokes her head out, and yells, "SPIKE!!"
"Oh, that's cool!" Although it seems like it would probably be...traumatizing...to come into existence in the middle of a battle. "In Equestria all ponies are people, plus dragons and gryphons and a few other species. What are most people in your world like?"
Before Katixa can answer, a tiny* purple-and-green dragon arrives at the door.
"Hey Twilight, what's—whoa, what is this place?"
"It's a long story. If I leave I can't get back in, so can you go tell the other girls to meet me here?"
"Sure."
(*) Probably just Small, in Pathfinder terms, though relative to the typical size of a dragon he's tiny.
They have all by now learned to ignore Pinkie Pie being Pinkie Pie.
"... anyway, Katixa, these are my friends Applejack, Pinkie Pie, Rainbow Dash, Rarity, and Fluttershy," says Twilight, pointing out each of them in turn. "This is Katixa, she's from another world."
"I wish I knew, but basically this restaurant somehow connects to a bunch of alternate universes. The one Katixa is from has evil gods so I was going to ask the Princess if there's anything we should be doing about that."
To Katixa—"Can you summarize the whole 'evil god' situation in a bit more detail?"
"Oh, well, the one who had the country we are working in is named Asmodeus. He's very bad. He's the Lawful Evil god of tyranny and slavery and he rules Hell. But the Glorious Reclamation, that's the paladin order I belong to, and some of its allies, conquered his country Cheliax away from him, and now we're Gloriously Reclaiming it. Except that after the fighting part got over with, this is mostly about riding around together so my paladin can be a judge for a lot of people who don't have a good judge, and he does not like it at all. But now we're in a city doing government things and I think that is better for him even though we do not get to spend as much time together."
From the connotations the translation effect is giving her for 'adventurers', it sounds like the word does describe her and her friends, and only them in all of Equestria. If Katixa's world has a standard word for it—well, she already knew that the other world had a lot of problems.
"I think you could reasonably describe us as 'adventurers' but I don't know how powerful we are by your world's standards. It sounds like your world has a lot more, uh, adventure going on."
"... there actually isn't really anyone else here who does what we do, and we can't abandon Equestria even if your world needs help a lot more, which it sounds like it might. But Equestria is always interested in making friends with people from other places, and that's also part of my responsibility, so I do want to visit your world. But I'm going to write to the Princess first and explain the situation."
She has Spike scribe and then send a letter briefly explaining the situation, including the interdimensional bar and the alien and the evil gods.
Dearest Twilight—
Actually, no, this is too bizarre a situation to be resolved via letter.
Teleport.
(There is a flash of golden light, and a white winged unicorn twice Twilight's size—though still smaller than Katixa—appears in the library outside the entrance to Milliways. She's wearing royal regalia and her iridescent mane streams out behind her without any apparent wind.)
Twilight looks back to Katixa. "Sorry," she says. "I wish we could have been friends. But she does have a point. It sounds like your world has a lot of problems that Equestria really isn't prepared to deal with, and it's probably better if we aren't connected."
"... you probably shouldn't, actually, mind him. That's Discord; he kind of does what he wants, and he says a lot of stuff that doesn't make any sense. Usually it turns out all right in the end."
(If Katixa has any kind of aura sight, Discord is blindingly Chaotic but not, actually, Evil.)
"Anyway, we'd still love to visit your world, and since the door on our end appears to be closed, it can't hurt Equestria." Also, depending on whether it still works this way after Discord messed with it, time may or not be passing in Equestria right now at all.
"Of course! I think that actually no time is passing in Equestria right now, if this place works the way it claims to, but either way a door that's only open briefly provides a lot less opportunity for evil gods to get into Equestria than a door that's open all the time. Or maybe we won't end up going home by that door at all. One of the things I want to do in your world is see if they know any other magic that might help us get home."
Twilight continues to be confused about what a 'god' is but she can probably figure that out by visiting the 'church'.
"Alright. I think that for the door to continue working you need to stay here, is that okay? If you tell us how to find your 'paladin' we can find them and bring them here so you can talk, since it sounds like you can't talk outside of Milliways?"
"I know a spell for translation, I hope it works on two-legged people. We'll try to find him."
She casts Starswirl's Universal Translator* on herself and steps through Katixa's door. Her friends follow her, though they're hanging back, since they don't speak the language. What's on the other side?
(*) Literally just Tongues, since MLP might as well run on Pathfinder rules if it needs to have a coherent magic system anyway. Mechanically, Twilight is currently an Arcanist** 12 / Archmage 1 with some custom feats.
(**) Not quite, but explaining the subtleties would require a whole essay on Pathfinder reification that I'll write in some more appropriate forum.
Katixa was going into the stable from having gone out in the yard, so the door leads into the yard when she opens it going the other way. It's summer out, and the yard is green, with a trampled dirt path from the stable door (that they're now emerging "from") to the rectory in the one direction, and another to the sanctuary in the other direction. There's an apple tree and a neglected kitchen garden and a stone bench that has had some of its edges chipped away and an actually paved path to the street, through the gate in the fence.
(When it was an Asmodean church, the stable was not horse-operable, but a Reclamation paladin on assizes stopped in Westcrown a year ago and had the mechanisms changed out while he was there, just in case, even though he didn't have a magic horse of his own.)
The temple of Iomedae is whitewashed, large, and bustling. Everyone there is very busy, or is waiting for one of the busy people and getting in the way while they wait.
Still, a pastel pony is a distracting enough sight to briefly get everyone's attention, a cascade of people seeing her out of the corners of their eyes and turning their heads and alerting people who didn't spot her on their own.
A couple people draw swords and a few other people head for the far exit.
"We're from another world and got here mostly by accident. I can demonstrate this if you follow me to the stable. Our intentions are friendly and we definitely don't mean anyone any harm...unless they're an evil god I guess, I've heard this world has those."
Why is this happening. "Please excuse me," he says to another person emerging from the meeting room, and he wades through the remaining crowd to approach her. "- okay," he says, when he sees the portal, "so... there's a portal, and also all the horses that were inside the stable are now trapped there?"
"From my perspective, my closet was suddenly replaced with this room just like your stable was. I went in, and while I was inside, Katixa came in. I don't know what happened to the rest of your horses—actually, I think if you closed the door and then reopened it, you could get back into the building that's supposed to be there, but then you'd probably lose access to Milliways, and access to Milliways seems quite valuable in addition to representing my friends' and my most likely chance of getting home."
Blai looks thoughtfully at the portal for a minute, then looks over his shoulder. "Lieutenant Sauer? - has anyone seen - you there, would you like to run an errand for the Church, help out some of the paladins' horses -"
"Yes, Select?"
"Hunt up someone who can cut a hole in the side of the building neatly and hang a new door in it."
"Yes, Select." Off runs the randomly chosen citizen.
"Yeah, that's a good idea," she comments. "Anyway, the particularly valuable thing about Milliways that I've discovered so far is that if you're inside with the door closed, no time passes on the outside, and also you can buy books from—a very large number of worlds. I couldn't get a clear answer on how many worlds there are exactly but it's apparently larger than my language has a word for."
"... uh, there needs to be someone from your universe inside holding the door open at all times, and Katixa will probably get bored of that eventually, but I can't think of anything more urgent than that. As far as I know time is literally stopped in my world relative to us."
"He's not in but I would expect him to come back before nightfall. Ah, intervention budget is a limitation observed by gods seeking to influence the material plane. They would often work at cross purposes or simply exert too much power to be safe for mortals and our environs otherwise - or there may be other reasons, I have no expectation we've been informed of the full picture - at any rate, all of the books throughout Creation are copied to the First Vault in Axis, but one does not go book-shopping in Axis because this would be staggeringly expensive, due to the need to compensate the expenditure of that budget in addition to the materials and labor of the book itself."
"No, I don't know what those are either. It sounds like a kind of spellcaster—I don't think we have spellcasters who were empowered by someone else, what would that even mean...um, I guess Princess Celestia made me an alicorn* and that made me more powerful, but I could already do magic before that and she definitely doesn't do it regularly."
(*) Tongues makes it obvious that this is the kind of pony Twilight is, with both wings and a horn.
"I'm a cleric. We are a kind of spellcaster; we can't cast spells without the endorsement and backing of our patrons and are chosen for this privilege by being well-suited to advancing our gods' interests in the Material. Acting by proxy like that is presumably less expensive than most other ways of affecting things."
"Yeah, we don't have that. Uh, as for Milliways, I don't know who or what created it or made it connect to our worlds, but it seems like if they had made an agreement to limit their intervention in your world then they would ... not have done that, it seems like a pretty extraordinary intervention even without the books. The book prices are reasonable."
"Also, I should bring this up now, I'm using magic to speak your language and it will only last about two hours. Milliways has a permanent translation effect but it only works inside."
"You should check that it works before you prepare it multiple times, I think that even if I learned your language nonmagically I couldn't actually speak it, my mouth physically can't make a lot of the sounds. I was a little surprised that this spell works—on that note, I want to try teaching your awakened horses our language, I think they wouldn't have that problem and then they'd be able to communicate with you if they had this spell cast on them." Actually she'll get Fluttershy to do it, probably she will end up with more important things to do.
"I know of a technique for making spells permanent, but I don't know it by heart and all my books are back at home. Do you have that here?"
[tl;dr of the previously promised essay: Twilight is a nonstandard sorcerer/wizard gestalt that gets both prepared and spontaneous spells out of a common spells-per-day cap. I'm not sure whether she has two casting stats but she might.]
"If you aren't able to replicate, uh, whatever it is she said, a lot of ponies in Equestria would be very happy to trade with your world—or, uh, at least the factions in your world that aren't evil. You'll need to persuade our Princess to allow contact, though; she's very concerned about your world's evil gods getting into Equestria. That's one of the reasons we're stuck here."
"... also, uh, say more about the resurrecting the dead thing?"
Yeah he was not expecting to get two chances to memorize surprise diamond farming information. He ignores Twilight till he's confirmed that the random person he assigned to writing things down has succeeded insofar as that was possible and tells them to find a wizard who can copy it and give it to Lt. Sauer along with an explanation to send along to important parties.
"- I'm sorry, I've missed some of what you said."
"The main obstacle to trade between our worlds, for diamonds or other things, is that our Princess is concerned about your world's evil god situation leaking into ours, but, uh, I don't think I actually understood the evil god situation very well when I told her about it, so—is she right to be worried?"
(It occurs to her that she didn't ever check whether this man's god was evil, but probably if he served an evil god this would be—obvious somehow, right?)
"I'll tell the Princess that whenever I see her again. How do you tell if somep—I mean, someone is good? I mean, most ponies are but if they're not they're probably going to try to hide it."
"... also, did you actually say earlier that your world can resurrect the dead?"
"There are spells that detect alignment but only in sufficiently powerful people, empowered followers of gods, and outsiders and the undead. And yes, there are several spells that can raise the dead with different sizes of diamond and circle of spell trading off against different intactness and age of remains available. I can't do this personally but I have used a scroll of Raise Dead before."
"That's—I know some ponies who would be very grateful if your people could do that." She's suddenly very glad Applejack can't understand their conversation, in case it turns out not to work on ponies or something. "Our world can't do anything like that, aside from—rumors of old dark magic that most ponies won't talk about even though they think it's a myth. Sombra's empire—" She shudders.
The fact that they have an established compound word for 'death magic' is concerning but not actually the most concerning thing she knows about this world. "I was assuming so," she says. "Do you know anything about what happens to people after they die? We don't—well, I don't." Celestia and Luna probably know if it's possible to know at all, but they haven't seen fit to tell Twilight.
"—obviously you shouldn't let the forces of Hell rule countries" (what the fuck!!) "but if a third of people go there anyway—actually, you know what, I need to talk to my friends about—all of this. One more question, though: Katixa said your world's magic would probably be able to get us home but it might be very expensive. Who would we talk to about that, and do you think we'd be able to pay them in diamonds after we made it back?"
"For that you want a Plane Shift. I'm not actually sure who there is in Westcrown - that's this city - who can cast it, apart from the archmages, but you might be important enough for archmages; the Arch-healer Naima has regular hours at the larger Temple of Abadar, and Archmage Cottonet is generally present at the Constitutional Convention, which... you are not straightforwardly admissible to but I could perhaps beg a moment of his time tomorrow on your behalf. Anyone with the ability to defend diamonds will accept them as currency."
"I'm Princess Twilight Sparkle—well, I've only been a princess for a few months, Celestia and Luna are the ones really in charge. These are—oops, it looks like my friends went back inside. I'll have to introduce them once I can get them a translation spell."
"... speaking of that, we're probably going to stay in Milliways, but we might want to explore the city, is it okay if we come and go via your yard?"
"Alright, I can Teleport out if there's an emergency, or more likely just go inside and shut the door—it's just that your people seemed alarmed to see us and I'd like to avoid a repeat of that. Also don't forget about sending someone to relieve Katixa of door-holding duty."
"You aren't a common race. I don't confidently expect you to have trouble - if nothing else the Arch-healer has turned people into more bizarre things reincarnating them into younger yet randomly-selected forms. I am considering who to send in after Katixa, this is neither obviously within anyone's job description nor an errand that any random churchgoer could perform, and it will have to be someone who isn't likely to be needed in an emergency. ...actually, I should decide on someone sooner than later, as Ser Goés should he run into any trouble of his own can probably summon her to his -"
"The door to it appeared where my friend Twilight's closet was supposed to be. Princess Celestia said it was dangerous for some reason and closed it, but Discord played a...prank" (she looks very disapproving as she says this) "on us so that we ended up stuck here instead of back in our world."
"Princess Celestia is the ruler of Equestria! She's an alicorn like Twilight, but she's a thousand years old and very wise and very powerful. She raises the sun every morning—well, in Equestria, I don't know who's responsible for the sun here."
"Discord is, uh, the Lord of Chaos. I really don't know how to explain him, except that he's very rude."
"Nightmare Moon—uh, Princess Luna—is Celestia's sister, a long time ago she got jealous of her sister and tried to take over Equestria, so Celestia banished her to the moon for a thousand years. Last summer she came back and tried to bring eternal night to Equestria, but my friends and I learned to use the Elements of Harmony to, uh—turn her back into Princess Luna? Come to think of it I'm not exactly what sure what happened there, but Luna is still around and isn't evil anymore."
Can she, now that she's an alicorn, cast an antimagic field powerful enough to nullify the Milliways translation effect itself and let her speak to Rarity in secrecy? Maybe, but she's not here to show off. Much simpler just to pull Rarity outside.
"There are evil gods here who have human servants. I doubt that man is specifically one of the human servants but they can certainly read a newspaper. I don't think we're going to be able to hide our existence, but I would like the evil gods not to find out about our unexplained ability to repeatedly handle problems way too big for us in the span of half an hour until after it's too late for them to do anything about it. Likewise the fact that diamonds, which are apparently absurdly valuable for magic here, are comparatively not scarce in Equestria. And—probably half a dozen similar things that we don't know about yet."
She lets out a dramatic sigh. "Alright, fine."
She goes back inside to the Inquirer. "Twilight says I shouldn't tell adventure stories because we don't want to reveal our capabilities. Want to hear about Equestrian fashion?" She can probably come up with a treatment of it that avoids mentioning the absurd quantities of gemstones.
Elorri gets home from his errands, greets Katixa, and is very surprised that she's pulling him toward the portal and has to make her stop and confirm with Select Artigas that as far as he knows his horse hasn't been enchanted and there's just a portal there now and in the associated demiplane Katixa can talk. Elorri lets Katixa pull him in when she resumes trying to do this.
"Hello!" says a tiny purple unicorn. "Are you Katixa's paladin?"
(Twilight has spent the last while discussing their situation with her friends, which discussion ended with the fairly unanimous conclusion that, while they should prioritize getting home and definitely not try to fight any evil gods unless Princess Celestia says it's a good idea, they should push back if Celestia tries to totally cut off contact with Golarion. It seems like they can really do a lot of good here, and the risks seem to be at least possible to mitigate.)
Katixa may not have anything specific to say but she is excited about trying out being a chatterbox to her bemusedly affectionate paladin. They go find a corner and chat. At one point Katixa raises her voice a bit to announce that she definitely knows without having to be told that just because she can talk now is no reason to tell Elorri anything that somebody told her because she couldn't talk at the time, That Would Be Wrong, and Elorri tells her he is so proud of her.
After a while it becomes clear that actually Katixa is delighted to have the important job of standing in Milliways holding the door while Elorri doesn't need her to ride across the countryside or charge into battle with him, so the Inquirer can be dismissed.
If she'd known that the Inquirer was reporting to Blai she wouldn't have cut Rarity's interview short! Blai is not a servant of an evil god and he should know about their capabilities! Well, it's probably still better to tell him, or one of the paladins, directly.
Milliways doesn't exactly have a day/night cycle, but the sun eventually sets outside, and it's probably well after sunset relative to the time they got up that morning. Eventually they figure out how to rent a room and head up to it.
They share a room; in Ponyville they all have separate houses, but ponies are still herd animals at heart, and in a new and rather frightening place there's something deeply comforting about all sleeping in a big pile.
“I do expect that, in reality, there are not. Most departed ponies choose to be reincarnated in Equestria, and those that choose to pass on into the River are informed of the reality of judgement before they choose—and, also, there are very few Evil ponies to begin with, and fewer still that die a normal death.” Most ponies who would plausibly have gone to Hell are instead statues in Celestia’s garden, but she’s not going to say that.
Luna sees where they’re going with this, and she doesn’t at all blame them, but no, actually. “Yes, Celestia and I made Equestria a place where it’s possible to produce diamonds and other gemstones easily, because they’re useful for magic in general. But I fear that the gods of Golarion would take offense, if we—”