Canterlot High-
The girls are standing in front of the portal to Equestria.
"I can't believe you're going to live in the same world as Princess Twilight!" Fluttershy squeaked. Sunset Shimmer smiled modestly. Her backpack for Equestria was so heavy, she stumbled as she walked. She opened Princess Celestia's book and began to write a quick letter to Princess Twilight, and wrote the precise details about when and where she will meet Twilight-- Just like she had the last 20 messages she'd sent.
"You're so lucky, Sunset Shimmer. Can you say hi to her for us?" Rarity exclaimed. "But of course, it will be... different, not being able to see you everyday."
"It's not so bad! I'll use Princess Twilight's portal occasionally and visit you guys for a couple of days. And besides..." Sunset replied, with a tight smile, "...I'll be figuring out who I'm supposed to be... in the world where I was destined to live in the first place." She frowned and looked down at her feet. The other students exchanged looks.
"Why so upset, Sunset?" Applejack asked as she put her hand on Sunset's shoulder.
"When I left Equestria, I may have... disappointed some Canterlot royalty. I just hope that they'll forgive me for being so..."
"I love guessing games!" Pinkie Pie exclaimed excitedly. "Ooh, I know! Disloyal?"
"Pinkie!" the students yelled in unison.
"No, no... it's okay, girls. She's right. But I've changed, and it makes me feel better knowing I'm not..."
"Ridiculous and disloyal?" Pinkie finished.
"Exactly," Sunset said with a smile. She looked around at the tall building of Canterlot High. She sighed. "I'm sure gonna miss this place, even if I don't have the greatest reputation here. This place may not be connected to me, but it's a bigger part of my life than Equestria has been." The students stood in silence. "And now I'm going to go to the person-- er, pony who solved all of the cold conflicts here and turned me around-- Princess Twilight Sparkle."
"Alright, so you're gonna be Twilight's student in some other dimension called Equestria where a bunch of colorful horses, unicorns and Pegasi live. Makes perfect sense," Rainbow Dash said sarcastically, adding in a chuckle. The students glared at her. "I mean, yeah! Makes perfect sense! But have you thought this through?"
"Yeah!" Pinkie said out of nowhere. "Where are you gonna live? What kind of job are you gonna get? Does Twilight even have her own school?"
"Well, I, uh, haven't come up with the answers to those questions, but I have thought about them," Sunset replied after a pause. "I think Princess Twilight has it all in hand-- er, hoof. And she doesn't really have an official school, but she agreed to be my own mentor despite the fact that she is very busy running her own kingdom now. I really need to remember to speak in Equestrian instead of using human phrases..." Sunset paused and smiled. "Wait a minute. You know what this means, right?"
"What... does this mean?" Fluttershy asked, barely audible. She stood very still as she stuck her hand out into the air as a butterfly landed on her index finger. Pinkie suddenly hopped towards Sunset's direction.
"You're gonna start up a restaurant in the other world?" Pinkie guessed. "If they don't have restaurants, then you'll be the very first horse to 'invent' one in your world!"
"That's kind of what I'm saying," Sunset replied, "but without the restaurant part, as there are already restaurants in Equestria. I can team up with Princess Twilight and write maybe a little book about humans." Sunset twisted a lock of her red-and-yellow hued hair and frowned. "Just as long as other ponies aren't as cynical as they probably will be once they hear about some new creatures discovered in a different dimension."
"Oh, don't worry. I'm sure you'll do fine!" Rarity said. Rainbow Dash looked up at the sky as if she were thinking something, then at Sunset Shimmer.
"I have a different theory," Rainbow interrupted. "If somebody suddenly came out of that portal and told us they were from a magical world with unicorns and magical powers and princesses, we probably would have laughed at them and walked away."
"I agree with Dash," Applejack said. "The ponies in the other world probably have their own feelings as well. Twilight and Sunset have demonstrated just that. And although I don't see anything relatively horse-like about them..." Applejack stopped herself and looked at Sunset. "Uh... no offense."
"None taken," Sunset said, adding a little giggle.
"Right, well, as I was saying," Applejack continued, "was that although I don't see anything relatively horse-like about them, they're definitely human-like. The ponies in this other world would probably feel the same way if Twilight and Sunset claimed that they saw these different creatures called 'humans' in a different world."
"Exactly!" Sunset said. "It would just seem awkward if that came up in a conversation, unless it was a discussion with Princess Twilight. But I don't know what we could tell each other about this world that we didn't know already." Sunset grabbed a pebble from the ground and tossed it into the portal as a test. It went right through the portal, meaning that it was ready. "Although, of course, there are definitely stories that I could tell her."
"I'm guessing they're from old Sunset Shimmer's times?" Rarity guessed, smiling kindly so she didn't accidentally hurt Sunset.
"Uh... pretty much." Sunset smiled. She checked her watch. "Guess I'd better get going. I'm supposed to meet Twilight on the other side of her portal soon."
The girls group-hugged and waved Sunset Shimmer good-bye. Sunset stumbled while she was walking in the direction of the portal.
"You'll make sure to come back sometimes, won't you?" Fluttershy asked.
"And make sure to dress well for the Grand Gala thing you were talking about!" Sunset opened her mouth to reply to the two, but she was interrupted by a "Wait!"
"Make sure to drink some root beer too!" Pinkie called after Sunset, who was about a foot away from the portal. Sunset and the other students looked at Pinkie in a confused way. "What? Everybody deserves to drink root beer." The other students chuckled or face-palmed.
Sunset waved good-bye as a mixture of "Bye!"s and "See you soon!"s followed her into the crystal-clear, brightly-colored portal, home to the detailed horse statue.
Through the portal, into the Equestrian world...
Sunset Shimmer let out a yelp as she tumbled out of the historical portal. Confused, she heard a crash. Upon realizing that the sound she heard came from her crash-landing, she looked guiltily at the scattered papers and books. She heard the sounds of galloping drawing near, and heard a female voice through her ringing ears, "Sunset! Are you alright?"
"Princess Twilight?" Sunset asked as she teleported to the purple Alicorn mare standing tall in front of her. She wasn't wearing her crown, but her wings were stretched and ready as though she were about to fly. "Sorry I'm a little late. I got caught up in the exciting but depressing state--"
"--of goodbyes," they both said in unison. They giggled and hugged. Sunset had learned when to do that after she'd discovered friendship.
"Now that you're here, why not let us give you a tour of my castle?" Twilight asked. Sunset looked around the room uncertainly.
"Who else will be assisting you?" Sunset asked. Twilight giggled.
"Oh... yeah." The purple mare excused herself and flew into the hall. Sunset heard the distant calling of "Spike!" A minute later, Twilight was shoving a small purple dragon, Spike, through the entrance to the portal room. "You... remember Sunset... Shimmer!"
"Twilight!" Spike complained. "Why do you always ask me to give tours of your castle? I don't even know this place as much as you think I do!"
Twilight smiled sheepishly at a giggling Sunset Shimmer. "Sorry, Sunset. I guess Spike accidentally left his manners at the entrance of Donut Joe's place." Twilight frowned and looked at Spike. "And all of those 42 donuts are coming out of your allowance, pal!" Spike looked like the donuts were about to come right back up again.
"Twilight! Should I get a paper bag? Where are they?" Sunset asked in a panic. Twilight smiled.
"No need to worry, Sunset. Spike normally does this when he's about to receive--" A blast of fire hurled out of Spike's mouth as the two ponies ducked. A scroll with an elegant bow dropped into the magical grasp of Twilight's magic. "--a message."
"Fascinating!" said Sunset. "A baby dragon who can talk and works as a mailing system!" Spike face-clawed. "So what kind of messages are these? Where are they from?"
"Well, they're normally from Princess Celestia..." Twilight said as she unrolled the scroll. "Like this one!" Twilight cleared her throat and read the scroll out loud:
My dearest, most faithful Princess Twilight,
I understand that Sunset Shimmer is now interested in finding a home in Equestria. Please ask her to visit me as soon as possible.
-Princess Celestia
"Oh dear," Sunset said with a sigh. "With all the excitement today, I almost forgot about my past. Almost."
"Looks like we'll be heading to Canterlot then. Come on, Sunset! We need to get to the train station before we miss the train to Canterlot."
End of Part I.