Image imported from “derpibooru”:https://derpibooru.org/3045220
Original Description:

Human Sunset entered the portal and got sent into what looked like a spiraling wormhole, before being teleported to an old and dusty looking library. Although Princess Twilight was mostly focusing on her royal duties, she had already ordered several of her royal guards to carry a majority of the moving packages and items from the Castle of Friendship to Canterlot, and more specifically, the castle which once belonged to Princess Celestia and Luna. Twilight had already finished packing everything the day before her coronation, and let the royal guards do their job as she was celebrating with her friends and getting used to her new responsibilities. However, one thing she also specifically did herself was placing the Crystal Mirror in the Canterlot library’s restricted section, as she wanted to ensure Pony Sunset’s entrance back home would be in a safe place, and she also wanted to conduct some research on the mirror itself in her free time.

The Crystal Mirror along with the entire convoluted setup Twilight had used to keep the portal open indefinitely was all intact and placed neatly near the library’s entrance, along with the old journal powering it up. As a result, when Human Sunset arrived, she fell onto the ground, but was rather confused at where she was now. Initially to her, it just looked like a creepy and old abandoned steeple with a library, similar to the building where those gang girls had taken her. She didn’t even immediately notice she was now in a pony’s body, as coming here to this supposed Equestria place entailed focusing on her main mission in learning what could’ve caused her seeming disappearance from her own world.

Human Sunset’s first instinct upon remembering this was reaching into her pocket to find that scroll piece again, only to find she had no pockets. In fact, she wasn’t even wearing any clothes now, and appeared to have an animal’s body from her waist-down. This was incredibly confusing and off-putting, the mere thought of her now being an indecently exposed filthy animal. But as she looked back onto the same mirror her pony counterpart had stared at admirably years ago, she suddenly saw a reflection of herself as a… horse? A four-legged animal, she knew that with certainty, but had no idea what this strange cone protruding out of her head was. Then, it suddenly hit her.

“Wait a minute…” Human Sunset said to herself whilst staring at her reflection, before getting on all fours. “Have I suddenly become that same four-legged animal in that dark area before I got engulfed by that void? It seems like I’ve become a horse from the looks of it, but I certainly look pretty strange for a horse. For that matter, I can even talk while being a horse? I’ve never heard of any animals talking other than parakeets, but… that’s besides the point. Where even am I, is this that Equestria place I read about in the diary? And for that matter, if I no longer have pockets, what happened to that-”

Human Sunset ruffled her hair to process everything, before noticing something falling out of her mane and onto the ground. Although she lost her clothes after transforming into a pony, the scroll piece was still intact and with her, but now it seemed awkward to pick it up, as she no longer had hands. She tried over and over to pick it up, but lacking fingers most certainly proved to be a challenge, not helped by the fact that being in this new place to her, raised far more questions than answers. Eventually, after being desperate enough to even get her mouth dirty, she instinctively just picked up the scroll piece with her teeth, unamused and also disgusted at putting something that’s been on the floor in her mouth.

“This is going to get really awkward if I stick around here, I just need to learn what’s been happening and why there’s an imposter back in my world.” Human Sunset said to herself in clenched teeth. “At least, I assume I’m now in a different world, since I don’t remember seeing colorful talking horses where I come from.”

As such, Human Sunset decided it was likely best to not stay here longer than she needed to, it was mostly a matter of learning where this fake Sunset had come from, and why specifically her existence created this detrimental effect to herself. The idea of magic being involved was still completely beyond Human Sunset’s comprehension, to where she decided to simply roll with it, realizing that whatever was the case, she had to know, one way or another. Given how this place was a library with shelves of books all over, it at least gave her the idea to read up on anything to help her understand, even if there appeared to be thousands of old books to choose from. This might be her only opportunity to learn what had happened when that void had taken her, meaning that even if she was going to be here for a while, so be it.

Since Human Sunset still couldn’t read what the scroll piece was saying, she released it from her mouth and placed it onto her hoof, which she was still getting used to having, at least for now. To save her the trouble of carrying it everywhere with her mouth, she tucked it into her mane, much like her pony counterpart did when she secretly took it from that history book back then. It was time to begin doing some heavy research, even if she had to do it one book at a time. Going off of what she already knew, she realized she had to at least look for any books revolving around the human world, a portal, and a void that trapped her. Unfortunately, much like Princess Celestia, who had already triple-checked and searched the absolute full extent of the library during her reign, Human Sunset wasn’t having any luck finding a book that was remotely relevant to the topic she was hoping to learn about.

Most books only elaborated on ancient spells and legendary creatures which had already been labeled as extinct from Equestria, but this at least let Human Sunset know for certain that she was now indeed in that Equestria place she was looking for. Considering how it was definitely likely for that imposter Sunset to return, which would potentially put her through that void nightmare once more, Human Sunset was adamant on ensuring she could completely understand what had happened, and if there was any way to prevent the imposter from coming back. The desperate nature of her research created a lot of noise as she was vaguely skimming the books for answers, which in turn, caught the attention of somepony who was finishing up organizing the outside Canterlot library, and was ready to hit the hay.

Twilight Sparkle had finished rearranging the library in a way that would help her find whatever she needed comfortably, as it was time to close up and rest for the night, since it was nearly 3 AM. However, the distinct sound of books being thrown to the floor began to vaguely make itself apparent, even if the library’s restricted section was a floor below where Twilight currently was. The princess followed the noise downstairs, realizing that someone had made their way into the one section of the library she still had yet to organize, which was also currently off-limits. Understanding the potential danger, Twilight quickly grabbed the secret books on the shelf that activated a hidden lever, opening up the entrance to the secret room. She also had her horn ready to blast magic, in case she had to fight this seeming intruder.

It didn’t make a lot of sense to the princess as to how someone knew about the restricted section, and why they were there this late. Since no one else seemingly knew of the secret area’s existence other than herself, Celestia, Luna, and Sunset Shimmer, Twilight surmised it was most likely someone who had a personal vendetta toward Celestia, or attempting to steal ancient Equestrian knowledge for themselves. Rushing in to find the intruder as quickly as she could, she eventually saw a trail of books on the floor, leading to a pile in the corner. This certainly gave off the impression that the intruder was looking for something specific, furthering Twilight’s concern to apprehend the culprit before it was too late. However, after searching another one of the rooms in this hidden library, the princess saw the pony who was responsible, and breathed a sigh of relief upon realizing it seemingly wasn’t someone dangerous or vengeful.

“Ohhhhh, thank Celestia.” Twilight wiped the sweat off of her face. “It’s just you, Sunset. I really thought for a second there that someone dangerous was robbing the library’s restricted section.”

“Errr, yeah, that’s right.” Human Sunset said, awkwardly.

Out of the fear that whoever was behind her would most likely notice anything different about her, Human Sunset didn’t turn around yet to reveal her face, as exemplified with the street gang from earlier, when one of them had claimed that the fake Sunset lacked eyeshadow, which she still had, based on the reflection she saw in the mirror. Human Sunset mostly tried to play things off, hoping that she wouldn’t get captured or punished for trespassing. It seemed fine though, as whoever had found her seemed to already know and trust ‘Sunset Shimmer’.

“Well, I guess it makes sense now why you’re here.” Twilight began surmising. “To my knowledge, you’re the only pony other than myself who knows of this hidden library, after Princess Celestia showed us how to get in last time. I’m also sorry for forgetting to mention that I had moved the Crystal Mirror here, just to ensure you’ll have a safe and easy way back into the Human World. But it looks like you found it on your own.”

“Thanks, I guess.” Human Sunset continued playing along. “You don’t mind the mess I just made, do you?”

“Oh, not at all.” Twilight reassured. “My hope was for you to get as comfortable as you’d like during your return to Equestria, and you’ve already mentioned to me that you’d be more interested in relearning magic, so it’s okay. I’ve said that I’m willing to give you that freedom in choosing when to level up in your studies, and promised I wouldn’t hold you back from trying to study new magic you didn’t quite understand, so you’re technically the only pony I’ve granted permission to be here, especially since you’ve been here before. Besides, I don’t mind the mess, considering I still have yet to reorganize this place in my own free time. In some ways, you’ve probably just given me a head start.”

“Alright, thanks for being so understanding.” Human Sunset breathed a sigh of relief. “By the way, what should I do if I find something in say… one of those books that appears to be written in a language I can’t read?”

“Oh?” Twilight said with curiosity. “Well for that, I guess you could use the archive’s mechanical catalog on the right from the main room. Remember when Princess Celestia showed us, but it broke apart after not being used for presumably hundreds of years? I already fixed it myself in my free time, but that catalog does have a translator if you’re having trouble reading something that’s in a language you don’t recognize. All you have to do is scan what you’re trying to translate under the bottom left scanner, then pull the right lever, which will print out what it says in English. And as far as I’m aware, it shouldn’t have issues with not recognizing any language, considering it’s a catalog that was specifically designed to organize ancient Equestrian books for many centuries.”

“Okay, I got it then.” Human Sunset replied, relieved that there was an easy way to translate her scroll piece. “Thank you very much for your help.”

“Anything for you, Sunset.” Twilight smiled. “But if you don’t mind me asking, why are you back here in Canterlot and doing research on magic this late at night? After our last meeting earlier, Starlight informed me that you were heading toward Silver Shoals to see Celestia, so I’m a little confused as to why you’re not only still here in Canterlot, but in the restricted section at nearly 3 AM. And speaking of, was there a reason why you didn’t let me know earlier that you wanted to come back here to do some late night studying?”

“Oh, I guess my plans just changed?” Human Sunset attempted to cover herself. “Plus, I didn’t want to interrupt you or anything, considering how busy you might be.”

“Oh, okay then.” Twilight understood. “Thanks for being considerate of me, since… yeah, being the princess of Equestria now isn’t the easiest job with how many responsibilities there are. But for the record, I’d still prefer that you check in with me from now on before coming here, just to ensure that I know for certain there’s no intruders trying to steal books or artifacts from here. I was admittedly worried when I heard noises down here, and all.”

“Alright, I will.” Human Sunset replied. “Thanks for being an understanding person- err… pony?”

“Still trying to adapt back into Equestria after living with humans, I see?” Twilight giggled. “It’s all good, I still remember that feeling myself, after all. Well anyways, I’ll be heading back to the castle and calling it a night, but if you’d like to continue doing some late night studying, I’ll let you do so. Though this means I’ll have to lock up the library for the night, meaning you might need to sleep down here until I come back to reopen the library at 8 AM. I’ve set up a bed in the left room from the main foyer, so if you don’t mind sleeping here for the night, I’ll give you that option. Or of course, you could use the mirror to return back to the human world to sleep, whichever works better for you.”

“Nice to know, but I guess I’ll stay behind here in the library for the time being.” Human Sunset agreed.

“Very well then.” Twilight nodded her head in approval at Sunset’s desire to learn, reminding her of herself. “Happy reading, but… try to at least get some sleep soon, if you’d like to see more of Equestria. And don’t forget, we still have to resolve things with Rainbow Dash with the rest of the council in the afternoon, so try not to stay up too late, alright? Good night, Sunset.”

“Good night… you?” Human Sunset said awkwardly, as Twilight trotted her way out of the restricted section, then exited the library, before using the key to lock the front doors.

“Hmm, is it just me, or was Sunset acting a little strange?” Twilight said to herself, as she was about to head back to her castle, before yawning. “Oh wait, that’s probably it. She’s most likely just tired, especially after everything she’s been through during her return to Equestria. Not to mention, wanting to work extra hard in relearning magic, even if she’s already earned her degree, I can respect that.”