Twilight Sparkle slowly rose from where she had landed. She was thankfully unharmed, but very sore, and more than a bit shaken. Though she was thankful that she knew her shield had worked, she was now faced with a new problem; as she slowly lifted her neck, she could see that she was surrounded by an arcane mist obscuring her vision. She figured that it must be a residual effect of her powerful shield slamming so hard into the ground, so she lifted her wings and brought them back down again to clear it away.
Now that she could see, Twilight noticed that she was in a forest somewhere, and that it was night time. Thankfully, Spike was right by her hooves, getting his own bearings back and otherwise looking fine. Twilight took a few ginger steps forward, thinking hard about her current predicament. She wasn't nowhere, which was a good first sign. However, the fact that she seemed to arrive in the middle of a forest at night made her think that perhaps she was thrown back into the timeline where Nightmare Moon reigned.
But she noticed that where she was looked nothing like the Everfree forest, and in fact looked much more like the forests near the Canterhorn's mountainside that she had grown up around. Though to be fair, she couldn't be sure anything would be the same as she had seen before. She wasn't able to dwell on this for long, however, before Spike pulled lightly on her tail.
"Uh, Twilight?" he said, staring at something behind her.
Twilight, however was too focused to give him her attention.
"Come on, Spike," she said while looking further into the forest, "We have to try to find the map again, if it's even still there..."
"Twilight..." Spike said while tugging her tail again.
"Hopefully this will still be fixable," she said while continuing to walk forward, "With any luck, the map could tell us where to- Ow!"
Spike had pulled on her tail once again, hard.
"What in the world was that for-" she began, but lost her train of thought once her eyes trailed from Spike to the object of his attention.
Right there, was an earth pony mare with a completely bewildered look upon her face. Lavender coat, midnight blue mane with purple and pink stripes, dark eyes, and a saddlebag filled with books and notes. A mirror image of the very same Twilight Sparkle whose tail was being held by Spike, minus the horn and wings.
The two shared a bewildered silence for a long moment before Twilight attempted to start conversation with the doppelganger.
"Um, hello," she said in a timid tone. "Uh, can I ask you some questions...?"
The other Twilight stared at her for another long moment, until she tried to rub her eyes clear, and then twitch her ears for a moment, and finally, laugh hysterically.
The alicorn Twilight and Spike shared a look, watching as the doppelganger continued to laugh in an unsettling tone. After a moment, her laughter subsided into giggles, until, with a bewildered smile upon her face, she pointed a hoof at the two and said "You're not real."
Twilight shared another look with Spike, then spoke to her unlikely twin again.
"Um, I know this might seem strange to you, but we're kind of in the middle of an emergency and we could probably really use your help."
The other Twilight giggled in an unbelieving way and said "No, no. You're not real, I've just wandered into the crash site of some kind of meteor and inhaled the fumes, and now I'm hallucinating! A-ha haha!"
Spike looked at her skeptically and asked, "Uh, are you okay?"
"Oh, and the talking dragon! How fantastical!" the hysterical Twilight said with a wild look on her face. "Aha ha, you look so real, wow!"
The currently breaking-down Twilight continued to giggle to herself and ogle at the others, while Twilight and Spike looked on with concern.
"Um," said the alicorn Twilight, "Maybe we should get out of the forest and work from there..."
The other Twilight didn't say anything or protest as Twilight gently led her away from the crash site and out of the forest.
Twilight gawked at the sight before her. It was Canterlot, as large and grand as ever, yet so different than the one she knew. Instead of the grand towers interconnected by sky bridges, supported by wide platforms jutting out from the mountainside, the city's buildings were laid out in stout rows along with the land. Though the white stone infrastructure and cascading waterfalls were still in place, Twilight could tell even from a distance that there was a distinct lack of the architectural styles that indicated the city's unicorn-built roots.
They city still retained its main entrance, which presented Twilight with a new problem. She looked over at her doppelganger, who seemed to be slowly coming to grips and worriedly examining the alicorn in front of her. If Twilight's hunch was right, the locals probably wouldn't handle seeing an alicorn very well either.
"So," she said turning to the earth pony, "What's your name?"
The other Twilight slowly looked up and locked eyes with "herself", a worried and skeptical look on her face. "Twilight Sparkle," she said simply.
"Oh, uh, me too, haha!" alicorn Twilight awkwardly laughed.
"You know what," Spike said, "I'm going to go ahead and fix this before it becomes a problem. I'm calling you--" he pointed at the alicorn Twilight, "--Twilight, and you--" he pointed at earth pony Twilight, "--Sparkle!"
"Sparkle" shot him an unbelieving look while "Twilight" just rolled her eyes, but continued to try and explain the situation to her double.
"So, uh, let me try to explain everything," she said, "So, where I come from, there's a pony named Starlight Glimmer. I guess my friends and I made her mad when we stopped her from doing some pretty terrible stuff, and she got back to me by -- and please hear me out here -- by sending us both back in time to a pretty critical moment in our worlds history. Well, she messed with a pretty important event, and I'm not completely sure what's happened, but somehow it's transported me over here. Does that make... any sense?"
"Sparkle" slowly nodded and said "Well, I suppose it makes just as much sense as talking to myself and a small dragon... Though, I'm not sure I actually believe any of it."
The two Twilights shared a long, silent look while Spike tried to get a better look at Canterlot in the distance. After a moment, he looked back to the two and asked "So, what do we do now? If we ended up here, who knows where Starlight could be!"
Twilight looked towards Spike and said "I don't know how to fix this, Spike..."
She looked towards her doppelganger again, and asked "So, uh, I could probably use some help figuring this all out. Maybe... Two Twilights are better than one?"
Sparkle stared at her again with hesitation, "Maybe I should see a doctor about hallucinating that I'm talking to myself first? Or at least call someone about the possibly dangerous gasses in the forest..."
Twilight groaned, "Alright, you don't believe this is real. Fair enough. Either way, with or without you I need to find a way to fix this mess, so can you at least tell me which way to fly from here to a town called 'Ponyville'?"
Sparkle scoffed, "Fly? What, don't tell me those wings are supposed to actually work on a pony's body?"
Twilight lifted an eyebrow, and with a slightly smug look on her face flew up into the air and hovered there while the other Twilight looked on in awe.
"Wait, so if you are real -- and I'm not saying that you are -- but if you are, how can you stay up like that with the weight of a pony? And how can you hover in place so smoothly without more rapid flapping?"
The Twilight in the air suddenly smiled knowingly, quickly forming a plan. She used her magic to lift Spike in the air and right onto her back, which only resulted in the grounded Twilight's eyes widening even more in disbelief and curiosity.
"I'll make you a deal. If you help me find Starlight Glimmer, how about I teach you all about magic?"
The mission back into Canterlot was almost ruined multiple times by Sparkle's incessant questions. As soon as Twilight turned Spike and herself invisible in order to covertly follow Sparkle back into Canterlot, Sparkle began a near constant state of questions that almost gave her away.
Thankfully, they were eventually able to get to her home and study without causing too much of a disturbance. It was a fairly ornate building built close to the cliff face, with a tower jutting out of the side and plenty of wide windows. True to form, most of the building was reserved for being Sparkle's personal study; though there was a distinct lack of the magic-based equipment that Twilight was familiar with, there were also several intricate mechanical devices that Twilight wasn't familiar with.
As soon as they were all inside and the invisibility spell was dropped, Sparkle began barraging Twilight and Spike with questions all over again, all while preparing various devices to study them further, as if it was never strange to be talking to herself in the first place.
"So it's like another type of force? Is it only created from organic beings or are there other sources of 'magic'? And what's the process to allow you to fly and turn invisible? Is it just reactive, or is there some sort of process you have to go through to activate it? And how does--"
Twilight stuck a hoof up to Sparkle's muzzle, "Wait a second now," she said, "I have some questions of my own right now. So this world really just... doesn't have magic?"
Sparkle shook her head.
"Wow," said Twilight, "In my version of Equestria, it's just as natural and immutable as gravity, or wind... What I don't get, though, is why this Equestria doesn't have magic. You see, Starlight was able to use her magic to send me back and forth in time over and over again, and even though each alternate future I landed in was different because of the things she changed in the past, it was never something like this. When she destroyed the scroll that allowed me to try and fix this, I think she might have somehow messed with the timeline even more than she had before..."
Sparkle held a hoof to her face in contemplation, "I won't claim to be an expert in magic or timelines, but couldn't you just make another scroll to send you back again and make things right without her coming with you and messing it up?"
Twilight rubbed her temples with her hooves and said, "Ugh, I wish it was that easy. Not only did she base her own spell off of a time spell that one of the best wizards ever known made, but to even perform a spell that like that she had to use another power source just to make it work. I don't think I'll be able to make, not to mention actually use a spell like that without the..."
Her head suddenly shot up, realization dawning over her face.
"That's it!" she exclaimed, "If the cutie map is still there, we might be able to use it to set things right! We might even be able to get help from our friends from this world!"
"Wait," said Sparkle, "You've lost me again. What exactly is the plan to fix all of this? And... What will this mean for my world? And, wait -- why should I even help you?"
Twilight scowled, "Well first, because it's the right thing to do! And secondly, if Starlight is running about this world with nothing to stop her, she could be really dangerous. When I first met her, she was using her magic to take away ponies cutie marks and indoctrinate them into her cult. And she had enough power to mess up the entirety of time, so I would say that it's probably within your best interest to help me stop this!"
Sparkle groaned and laid her head on her desk, "Ugh, why did it have to be my interdimensional twin..." she raised her head up to look back at Twilight. "Also, what's a 'cutie mark'?"
Twilight stoke a quick look at Sparkle's flank, which she had only just noticed was completely bare.
"Oh, wow. I guess I should have seen this coming... Uh, you see this symbol, on my flank?" she said while pointing to her own flank, "Every pony has a unique symbol of their own, called a 'cutie mark'. It's a representation of our special talents and place in the world; it's basically a magical mark of one's destiny and sense of self. For instance, mine represents both magic and my friends."
"Huh," Spike said, "I guess in the end Starlight got what she wanted, didn't she? A world without cutie marks, right? I wonder if the Starlight Glimmer from this world had any better a life because of it..."
Twilight's face turned serious in contemplation for a moment, "I have no idea, Spike. There's a lot we don't know here; I'm still only really guessing as to how this all happened..."
Her look of contemplation turned into one of determination. She smacked her hooves together in emphasis and said, "But I do know one thing; The best chance we have to figuring all of this out is to find the map, find Starlight, and most importantly, find our friends!"
Twilight shoved a hoof up into the air and took a heroic pose, "Onwards to Ponyville!"
Sparkle groaned, "Can we at least wait until the morning? It's almost midnight right now..."
Twilight put her hoof down as a sheepish look came upon her face, "Oh, uh, right. Onwards to Ponyville in the morning, hehe..."