It was a beautiful day at the Castle of Friendship. The sun shone pleasantly through its many windows, sending prismatic rainbows bouncing off of the solid crystal structure and blinding the occasional unfortunately-positioned passerby. With a surprisingly slow schedule for the two-person staff this week, it was a good day to relax and do something fun – which, for one member of the “staff”, currently involved roaming the halls with her face buried in the newest book by an expert in the field of theoretical quantum magiphysics.

Twilight Sparkle, Alicorn Princess of Friendship, flipped a page of the book that floated in front of her in a cloud of pink magic, violet eyes scanning the words with an air of intense concentration. Another cloud of pink flared to life at her side, lifting pencil to paper and scribbling hurried notes. “The Rhinestone Theory does compensate for some of the spacial differentials, but this alternative balancer to the dimensional matrix seems highly unorthodox. Surely somepony would have realized by now if all that was needed was the same basic spell formula behind creating Soupy’s Soap Bubbles!” She paused both her writing and her walking for a second, then continued. “Actually, I can absolutely see why nopony thought of that. I'll need to do some tests to verify the hypothesis, ooo, this is going to be so much fun! I’ll have Spike go shopping for—”

She was five steps past the small dragon waving for her attention before he cleared his throat. “Hey, Twilight, hold up!”

Twilight stopped and spun, beaming her number-one assistant a big smile. “Oh, Spike! I was just looking for you!”

“Yeah, I could see how hard you were looking,” Spike quipped. “It still freaks me out how you can walk and read and write without smacking into things.” He trotted the last few steps to catch up with her, one of his ear fins cocked in the air.

“Peripheral vision is greatly under-appreciated,” Twilight quipped back, magically snapping the book closed as she considered the short purple-and-green dragon. “Sorry, you know how I tune things out when I’m focused. I need you to— Wait. You were trying to get my attention. Did you need something?”

Spike raised an eye ridge in disbelief. “Well, I wouldn’t say it’s me that needs something… You’re telling me you still haven’t noticed?”

The purple alicorn paused then, finally really paying attention to her surroundings. She began to pick up on a distant, echoing sound of knocking, possibly coming from the castle’s front door…and, if she heard correctly, it was growing more and more frantic. Twilight’s eyes widened. “Someone’s at the door?!” She whirled around and flew towards the stairs, her pink magic carrying her book, pencil, notepad, and Spike. “How long have they been knocking? Why didn’t you answer it? We have GOT to get some kind of staff!”

“Just a few minutes, I ran into you first, and that’s what I keep saying!” Spike grumbled as he settled into the magical floating ride. The subject of hiring staff was an oft-discussed and equally-oft-forgotten issue, since, being that they lived in a magical self-maintaining crystal castle made of the power of harmony and rainbows, the need for extra ponies wandering around their home didn’t seem important most of the time. Except, of course, for occasions like unexpected visitors at the distressingly distant front door.

Her head whirling with a mixture of confusion over the anxious knocking (which had reached a woodpecker-like tempo), curiosity about who could be visiting (most visitors called ahead, and her friends just came in), and irritation at having her casual study of the fascinating field of scientific spell research interrupted, Princess Twilight Sparkle raced down the stairs, landed in the front hall, placed Spike and her supplies safely down, and opened the front door to her castle home.

“Sorry for the wait! Can I help—?”

“TWILIGHT SPARKLE!!!” The wail that greeted Twilight was so crammed with volume, relief, and frank panic that it blew the alicorn back a step. “Please, I need your help! I’m a human from another dimension and I woke up in this pony body a little bit ago and I have no idea how I got here and you’re the super-magical alicorn princess who knows how to handle this stuff and for pity’s sake can you help me get home?!? ”

Twilight Sparkle blinked, allowing herself a brief moment to assess the situation (and get her hearing back). Standing on the front step of the castle, hoof still outstretched from beating on the yellow door, stood a unicorn mare. Her coat was black, with a mane and tail in a bright combination of neon blues – and messy, as if the wearer had just rolled out of bed. A cutie mark of an unfamiliar pencil mechanism marked her flank, its tip trailed by a river of blue that created the overall impression of the letter "B". And right now, she was staring at Twilight with wild eyes, her chest heaving desperately.

The rest of what had just been said finally sank in. Twilight blinked again, opened her mouth, closed it again, furrowed her brow, opened and closed her mouth one more time, and shook her head. Then she stepped aside, frowning slightly, and said, “Perhaps you’d better come inside.”

Maybe the theoretical quantum magiphysics could wait.

----

Twilight decided to use the small antechamber off of the main hall; it wasn’t used very often, but it had comfortable furniture and was only a short walk from the front door. The strange mare now sat on one of the couches, making a visible effort to get a hold of herself. After summoning a tea set and offering a cup to her visitor, Twilight stepped out into the hall, with the parting reassurance that she would be right back.

“Spike, I need you to get a hold of the girls,” she said in a voice too low for their strange visitor to hear. Behind them, a sound like disgruntled muttering was followed by the sharp clack of something hitting the floor.

Spike saluted, shooting uneasy glances at the door. “You sure you wanna be left alone with her? She sounds a little…” He waved a green claw in circles by his right ear-fin.

“Please, Spike, I’m an alicorn Princess,” she said lightly, flaring her wings. It still felt weird hearing herself say that, but Spike needed the reassurance. “I’m sure I can handle one upset unicorn.” A thoughtful frown crossed her face as she added, “And maybe she’s not crazy. She mentioned ‘humans’ – that’s what my friends through the magic mirror are called, remember? I think I’d better hear her out.” Twilight nudged her assistant to get him moving before turning back to the door. “Let the girls know that it’s probably not urgent, but I’d like them to come by just in case.”

As she reentered the room, Spike’s running footsteps behind her made it clear how urgent he felt about the situation.

The blue-and-black unicorn snapped upright as Twilight came back in. She was smiling nervously. “Hi, you’re back. I’m so sorry, I can’t for the life of me figure out how you grip with these things…” The statement made no sense to Twilight - until she saw the teacup lying on the marble floor. That explained the dropping sound a moment ago. The black mare shuffled her hooves anxiously. “I don’t, uh, think it’s broken, but do you think you could…?”

Alright, crazy or not, this pony was definitely acting  like somepony – er, someone – who had never had hooves before. Twilight magically levitated the empty cup to the table, then filled it with tea and placed it front of the unicorn again. The mare watched this simple feat with the wide-eyed wonder of, well, somepony who’d never seen magic before. “It’s fine. The cups are pretty durable, and it’s easy to clean up in here,” Twilight said soothingly. As the mare oh-so-carefully pressed the cup between her hooves and clumsily raised it to her lips, Twilight settled onto the opposite couch. “Alright, I’m listening. Why don’t you start from the beginning?”

A huge sigh of relief whooshed from the unicorn’s mouth, her cup almost slipping from her hooves. “Oh, thank you. I thought, I hoped maybe you’d listen to me; I mean, this has to sounds crazy!  But I figure, you’ve at least met humans, with that magic mirror thingie, and you deal with crazy stuff all the time—”

“Hold it!” Twilight’s eyes widened. “You know about Canterlot High? Then that is where you’re from!” Well, this would be easy enough; they could just travel through the mirror and—

But the mare was shaking her head. Her ears lay flat; no doubt a blush had formed under her black coat. “No, no, sorry… Shoot, didn’t mean to make things more confusing. See, I’m a human, but I’m not...THAT kind of human. Like, your friends there are sort of the same as your friends here, with the bright color schemes and the themed names, right?” She waved both of her forehooves at herself, then flinched as her cup slipped and splashed tea on the cushions. “Dangit, sorry, anyway, where I come from, that’s not the case. Humans in my world are a pretty mundane set of colors, mostly different shades of brown, and there’s no magic. Well, that’s debatable, but we won’t get into witchcraft because I don’t like it—”

“But how do you know that?” Twilight interrupted, eyes narrowing. “You say you’re not from Canterlot High, or from Equestria, but then how do you know what humans in Canterlot High look like?” Another, equally suspicious thought entered Twilight’s head, and she found herself pacing the room, casting hard looks at her mysterious visitor. “For that matter, how did you know to come to me? You act like you know who I am already, which is impossible if you’re from a completely different world!” The more she rolled the idea over in her head, the more Twilight’s skepticism grew. This pony’s story just didn’t hold water.

Maybe Spike was right, and she really was crazy. Or worse…

The mare didn’t answer at first, massaging her head in one hoof and muttering something about “screwing up” and “way to break the space-time continuum”. She didn’t seem to have trouble holding her teacup now, but Twilight allowed for the possibility that she was too distracted to overthink the simple task. It had happened to Twilight when she'd had fingers. “Aaaugh, I didn’t realize how hard this would be to explain…” the unicorn sighed. Her blue eyes met Twilight’s, waves of uncertainty, fear, and, interestingly, frank stubbornness crossing her face. “Um... okay. I’m going to try and lay this out in a way that... makes some kind of sense?”

Twilight nodded. The unicorn took a deep breath, stroking her blue tail distractedly. “Okay, picture this. Let’s say that, where I’m from, we sort of... have a way of looking at other... worlds? Like yours? And Canterlot High? The point is, I know I’m not from those worlds, because with this... technology of ours, I’ve seen your world. And that one. That’s how I know that they’re different from mine.”

Twilight raised an eyebrow; her confidence in this story was not growing by great leaps and bounds. The unicorn must have sensed this, because she did a frantic erasure mark with her hooves. “I can prove it! For example, I know about your visits to the mirror world of Canterlot High. You stopped Sunset Shimmer when she stole your crown, and became a crazy demon creature, and tried to zombify the school. And then in the next mov-uh, visit, you helped your human friends AND Sunset stop the, oh, what’re they called... the Sirens! In a rock concert battle. There was a massive, magical unicorn in the sky. It was kind of cool,” she added with a distant grin.

“You know, you could know all of that because you came from that world,” Twilight pointed out delicately. She was the Princess of Friendship, she reminded herself, and Princesses of Friendship give ponies a chance to prove they weren’t off their rocker. At least the possibility of this pony being a spy felt less likely, unless she was just the most unconvincing and unprepared spy in the history of Equestria.

The mare facehoofed. “Right, okay. Sorry, I’m way better at explaining things in writing. Let’s try something more specific…” She pointed a hoof at Twilight. “Your world, then. With our, um, technology, I’ve seen a few things that aren’t common knowledge. Liiiike…” She thought for a moment, then brightened. “Oh, how about how you got your—! No, that’s no good, need something more current.” Twilight blinked, suddenly really wanting to know what she had been about to say, but the unicorn was already brightening with another idea. “The Cutie Map! You have that table that turns into a map of all of Equestria, right? When you defeated Tirek and got your new powers from the Tree of Harmony, it created this castle, and a 3D map that calls your cutie marks when it’s sending you on a friendship mission!”

Twilight’s ears perked upright, and she stopped pacing. It wasn’t exactly a secret that the table in the Council Room doubled as a magical map, and her friends’ families knew about it... but it wasn’t common knowledge, either. She frowned slightly. “Alright, that’s a little more convincing. But, I’m sorry, I still need more evidence than that.” While the idea of another alternate world with an unknown civilization that apparently lacked magic and yet had the capability of seeing into other realities fascinated her, Twilight kept reminding herself to be careful.

The unicorn chewed her lip, thinking hard. “Okay… how about this. I’ll name off the missions I know you guys have been on.” She held one hoof up, and pointed at the frog of it with the other. “First mission: all of you Elements of Harmony girls go to that weird, unnamed village where everypony has equals signs for cutie marks. Fluttershy saves the day by revealing Starlight Glimmer’s fake mark with water, and the villagers help you get your marks back before Starlight gets away.” Her hoof pointed at her other hoof again, though maybe slightly to the left of the last point. “Mission two: Pinkie Pie and Rainbow Dash go to Gryphonstone. Almost save the lost idol of something-or-other, but find out that the real mission was to help Gilda see the power of friendship so she can help the Gryphonstone gryphons get back on their feet. Pinkie Pie also saves the gryphonscones through the power of baking powder.” Another point, again slightly farther to the left. “And mission three: Rarity and Applejack go to Manehatten to help Coco Pommel organize a theatre event so the locals would realize the value of coming together as a community! Also, Rarity replaced Applejack’s old cowboy hat that got torn up.” She stopped and stared for a long moment at the hoof she’d been pointing at. “Man, that hand gesture works way better with hands.”

Twilight Sparkle realized that her jaw was hanging open, and snapped it shut. The unicorn quit studying her hooves long enough to notice this, and gave a lopsided grin. “It’s a little hard to swallow, huh?”

“A... a little, yeah,” the alicorn princess stammered, her mind working at lightning speed. The Idol of Boreous – Rainbow claimed they hadn’t shared that incident with anyone, in case it upset the gryphons to know their precious relic was lost for good. This pony definitely hadn’t been at Starlight’s village, either. And Applejack’s hat!

Twilight frowned again as something occurred to her. “You only mentioned three friendship missions, though. What about the mission Fluttershy and I took to help the Hooffields and McColts?”

The mare stared, blue eyes completely blank of comprehension. “The what with the who now? You did that? Nah, I don’t know what you’re talking about there. Must not be something I’ve seen yet.” A small grin crossed her face. “That sounds neat, though.”

That was a little comforting, at least; whatever method this pony was using to observe (or spy on?) her and her friends must not be entirely current. And, as much as she wanted to be cautious, Twilight had to admit one thing: it was hard to accuse a pony of lying when she looked and acted that clueless.

“So do you believe me now?” The black-coated unicorn watched her anxiously, pawing at her blue-striped tail.

Twilight took a deep, slow breath... and let it out as an amazed laugh. “I’ll admit, it’s getting a lot easier to believe your story.” She began to pace the room again, her scientific curiosity buzzing. “If what you’re saying is true… then, this is an amazing discovery! The idea of another universe with the ability to see into other worlds, and you say you do it without magic? I can only imagine the knowledge you gain from looking into other realities!” Hopefully it doesn’t involve anything too embarrassing for me and my friends, the logic centers of her brain noted, but she was too busy being fascinated to pay attention to it. Something else that had been puzzling Twilight suddenly fell into place, and she turned to face the mare. “So that’s how you knew to come to me for help?”

“Yes!!!” The mare bounced on the couch cushions, so giddy with relief that her smile was almost literally splitting her face in half. “Oh man, I knew this was a good idea! Yes, you’re kind of a big deal in our, uh, thingie, so I knew you were super skilled with magic and deal with bizarre problems like this all the time! Plus, I mean, you do magical research and stuff, and you have that mirror that travels to other dimensions, so if anyone could figure this out—”

“Alright, alright!” Well, that had been a bit more flattering than expected, although she wasn’t entirely sure how she felt about being the object of study for an unknown collection of otherdimensional beings. “I mean, I can’t promise I’ll be able to help, but… Look, we’ve gotten really far off track. Let’s go back to what actually happened to you, and this time, please try to tell me everything in order.” A gentle way of pointing out that they had been going on more rabbit trails than Angel Bunny at the annual Easter Egg Hide.

“Okay. Right. Okay.” The blue-maned mare took a deep breath to compose herself. When she spoke again, it was calmer and more deliberate. “Okay. The last thing I remember is, I was sitting at my computer, working on some writing.” She paused, biting her lip. “Um, do you know what computers…?”

“Yes, I know what computers are,” Twilight replied quickly, feeling a dash of pride at her human-based knowledge. She’d really been meaning to discuss the concept behind those portable machines to some of the technical institutes, computing technology was still ages behind—

“Great! Anyway, it was probably around 8 o’clock in the evening, and I was finally getting some writing done. Then all of a sudden, I feel this... buzzing, all over? It was really freaky, like the time I gave blood and almost passed out. The next thing I know, I’m waking up in a field, and it’s the middle of the day, which was an immediate red flag. I didn’t even notice the whole ‘pony’ thing at first because I was a little upset about passing out, I’ve never done that before…” She noticed Twilight’s motivating stare and took another deep breath. “Anyway, once I figured out what and where I was, and, you know, decided I hadn’t just lost my mind, I came to find you.” She flexed one of her forehooves, giving it a considering look. “You know, I always thought it’d be tricky to run on four legs, but it came a lot quicker than I expected. You guys get great shock absorption with these things.”

The mare fell silent at last, watching Twilight expectantly. Twilight, for her part, was glad of the silence. This wasn’t a lot of evidence to go on, unfortunately; a buzzing sensation, then blacking out? The physical transformation seemed similar to how the mirror affected a traveler’s body, so maybe it was a universal constant for dimensional travel. But for her to just be plucked out of the air? That suggested a powerful space-time anomaly, or perhaps some kind of magical intervention…

This would definitely take further study. Twilight stood to her hooves, eyes bright with determination, and was just opening her mouth to put her first plan into motion, when the door slammed open and ponies poured in like colorful floodwaters.

“Yo, Twilight!” Rainbow Dash was in first, followed closely by Rarity, Pinkie Pie, and Applejack. Spike managed to squeeze into the small antechamber as well, which, with six ponies and a baby dragon, had quickly gone from cozy to crowded. “Who’s this crazy pony Spike’s all worked up about?” Her pink eyes shot to the mare, and she frowned. “Is that her? She doesn’t look so tough.”

Twilight gave Spike a very pointed glare that sent the clear message of exactly how much she approved of his popularizing the idea that their visitor was crazy. She would have turned a similar glare on Rainbow Dash for saying it out loud like that, except Rainbow Dash wasn’t paying enough attention to notice. “Thanks for coming, girls. You got here faster than I expected!” She mentally counted her friends again. “Where’s Fluttershy?”

“Dunno where Fluttershy is, but we were over at Sugarcube Corner getting cupcakes for Gummi’s birthday party,” Pinkie Pie explained, and walked right past Rainbow Dash to stick her nose in the face of their guest. “Hi, I’m Pinkie Pie! Welcome to Ponyville!”

“Hi,” the mare answered back with a nervous smile.

“Spike said this here pony was claimin’ to be one o’ them humans from another dimension or somethin’,” Applejack put in, studying said pony with interest. “Ya look like a normal pony t’me, if’n ya don’t mind my sayin’, ma’am.”

“No, you’re good.”

“I for one am quite interested in hearing this story,” Rarity said, purple eyes shining. The six must have run to get here, because the pale unicorn was busily patting loosened hair-wisps back into her otherwise perfectly styled mane. “Twilight’s told us all about the human world, and I’ve just been dying to talk to one of you. You must tell me all about what the latest fashions are like!”

“Ah, she might not be from the same human world that I’ve been to, Rarity,” Twilight put in. This drew confused looks and a new slurry of questions from everypony, and suddenly Twilight understood why her visitor had looked so uncomfortable trying to explain this bizarre story.

It was during this time that some ponies began to realize that the black-coated mare was still looking expectantly at Pinkie Pie. Pinkie Pie, for her part, had decided that this was a staring contest; if it were, they would have been dead tied, because they’d been staring at each other without blinking for a good thirty seconds. But finally, their visitor tilted her head and asked, “Well?”

Pinkie Pie tilted her head right back. “Well what?”

“Aren’t you going to… I dunno, tell them my backstory or something?”

“Why would I do that, silly?” Pinkie giggled, then suddenly darted forward and touched noses with the stranger, eyes searching. “Do I know you from somewhere?” She gasped loudly. “You’re not my secret penpal from Gryphongolia, are you?! This is super, we are going to have such a cool party for you—!”

“No, nonono, no, I’m not! I just, it… it’s… it just seems like something you’d…” The mare groaned and put a throw pillow over her head, curling up like she might melt into the couch cushions. “Nevermind, just ignore that, please,” her muffled voice said through the fabric.

Twilight resisted the urge to chuckle, then scolded herself. No, she was a Princess! And until proven otherwise, this pony was a distressed traveler from another dimension, who needed help getting home. Exactly the sort of problem the Elements of Harmony could help with!

Twilight cleared her throat, drawing the attention of the girls (and Spike). “Well! Now that everypony’s here – except Fluttershy – I suppose introductions are in order! Girls, this is—” Twilight stopped. She spent a long moment frantically searching her memory as a deep, purple blush spread across her face. Finally, unable to avoid it any longer, Twilight Sparkle turned to the mare under the throw pillow and said, in tones of deep embarrassment, “I am so sorry. Here we’ve been talking all this time, and I never asked your name!”

“Huh?” A blue eye peeked out from around the pillow. “You di— Oh wow, you’re right! I was too freaked out to notice.” Setting the throw pillow aside, the mare sat up properly and dipped her head towards the general crowd of staring eyes. “I’m, uh, Jenn. Nice to meet you.”

“Ima Gem?” Twilight repeated. Well, it wasn’t the strangest name she’d—

“Wait, what? No, my name is Jenn. J-E-N-N. Short for Jennifer. Although I also go by River in some—” Jenn/River stopped suddenly and shot a suspicious glare at her B-shaped cutie mark.

Twilight searched her mental catalogue for information on the human’s name, in case it provided useful clues about her possibly-human guest. To her surprise, she came up empty. Almost every culture she knew of assigned some significance to their names, but the etymology of “Jennifer” was completely unfamiliar—

“What kind of a name is that?” Rainbow Dash asked, once again demonstrating her skill at wielding the Blunt Stick. “It sounds weird.”

Rarity jabbed her in the side, which started a glaring match between the two of them. “Well, I think it’s a lovely name!”

“I dunno, she looks more like a River Babble to me!” Pinkie Pie added off-handedly.

Jenn/River’s jaw dropped. “Did you just—?”

“Ya know,” Applejack cut in, shooting Rainbow Dash and Pinkie Pie a pointed look, “it might do us all a sight more good to here this pony’s story before we get lost fussin’ over what kind o' name she has.” The apple-farming earth pony turned to her purple friend and, in tones of great patience, said, “Maybe ya better fill us in on what ya know now, Twa’light.”

“I think that’s a good idea,” Twilight said, making a mental note to help Applejack clean out the barn this weekend as a much-deserved gesture of gratitude. “As I was saying… Jenn, or River, this is Rarity, Applejack, Pinkie Pie, Rainbow Dash, and you’ve already met Spike. Now, I think it would be best for all of us if you told them exactly what you told me.” And then I can get their opinions on what to do about it.

“Oh… right…” Jenn/River looked at each of the expectant faces staring at her. Her ears wilted, and she heaved a weary sigh. “Let’s see if I can keep it all straight a second time…”