Scootaloo found herself being awakened several hours earlier than she would have liked.
"Uh? Wha?"
"You need to get up, kiddo," Rainbow Dash said. "Pack what you need for an overnight. You need to be dropped off at the Apples."
"Huh? Why?" Fear was beginning to chase out her weariness.
"There's been an incident in Canterlot. The Elements of Harmony are needed. Sorry, but I need to..."
"What about our day out?"
"I'm sorry, squirt, but we need to postpone it. The Wonderbolts are on high alert too, so it looks like Soarin’ can’t come visit either."
"But..."
"Scoots... look, I really don't have time to argue, Celestia wants us at the castle." She was already at the bedroom door. "But life sometimes throws things at you that you need to sacrifice for. Be ready to go in ten minutes."
She left before Scootaloo could say anything else. The filly sat on her bed for a few moments, angry at being brushed off. This faded at the remembrance of Rainbow Dash's tone. That was her business tone, the one that said that something important needed to be done. She used it when making sure she was doing her chores and grades, when giving her explicit instructions as to what to do. Whatever it was, she was serious.
She sighed, grabbing her saddlebags and putting her schoolbooks and a single reading book in them, still regretting the weekend lost.
"Sunset?"
The unicorn in question looked up from her book with an annoyed look on her face. "What?" she asked, filling the singly syllable with as much venom as she could muster.
Her fellow student seemed taken aback by the vehemence, but they went on. "Well, we're going to be putting together a study group at Donut Joe's, and..."
"Wait, don't tell me," she said, putting on a transparently fake excited tone, "you want me to come along so you can leech off of my knowledge and kiss up to Princess Celestia's star student?"
"Uh... um... well, we did want you to come, but..."
"Yeah, thanks but no thanks. If I actually went, you idiots would drag down my GPA."
She returned to her book, just listening enough to hear the mare walking away, muttering under her breath.
She had only read a few lines until a new shadow blocked her light.
"Sunset..." Celestia said in a weary tone.
"Yes, Princess?" This time, she seemed genuinely happy.
"That wasn't how I was hoping you'd respond to that."
Sunset blinked. "What do you mean?"
"I asked her to invite you along, because I was hoping you would finally open up to your classmates."
"Princess, you told me I should always be seeking new knowledge. What could I possibly learn from ponies like them?"
"You'd be surprised. Some of the richest ponies in Equestria could learn some things from the humblest farmer."
"I fail to see how."
Celestia looked at her with clear disappointment, and Sunset cringed. "I'm sorry, but I just can't see... I try, I really do, but..."
"Sunset..." she interrupted. Then she sighed. "Please come with me. I need to show you something."
Celestia didn't lead her far, merely into one of the restricted rooms in the library. A simple spell opened the door.
Inside was a single object, covered in a thick tarp. Celestia closed the door behind her and locked it. After double and triple checking the spell, soundproofing the room and all, she lifted the tarp off. It was a simple mirror, full length.
"Now, Sunset... I want you to step forward, and tell me what you see."
Sunset looked at her reflection. After a moment, she let out her breath. Her mirrored self was growing wings. A crown of fire materialized on her head. It was grinning wickedly.
"I see... I see a pony destined to do great things... a pony capable of being a princess."
"...I see." Celestia sounded disappointed. "Is anypony with you?"
"Nopony but you. Why would there be?"
"That's enough, then," Celestia said, pulling Sunset away from the mirror.
"No!" Sunset screamed, pulling against her. She reached out, her hoof touching the glass. Her reflection also reached her hoof out, touching the other side just seconds after the real thing, almost as if begging. "What is this? Does it show the future? What?"
Celestia responded first by re-applying the tarp, much to Sunset's eternal displeasure. "This was a failed venture, according to me. The mirror was supposed to show you what you truly wanted on the inside. That power topped that list worries me."
"Wh... why? Magic is power!"
"No. It isn't. Not the most special magic. You need to understand that friendship and relationships are important."
"But... the mirror..."
"Enough on the mirror. I will give you a proper lesson on it in due time. Until then, I want you spending more time outside the school. Do you understand?"
"...Yes, Princess."
"So, wait... this mirror lets ponies see their true desires?"
"That's one function," Celestia said. The small room was now filled with the Bearers, all looking particularly annoyed at the early awakening. "But as you might have guessed, there is more. But the important thing is this: when Sunset looked into it and could only see herself ruling Equestria, I was scared. I vowed not to fail her as I had my sister... but it was a vow I couldn't keep. Sunset continued pushing me about the mirror, until finally one day, she disappeared through it."
"Wait," Rainbow Dash said. "If she was so insistent about this and you noticed all the problems, why'd you keep her around?"
"I..." Celestia took a deep breath. "I loved her then as I love Twilight now. I was all she had... she had no parents, no older brother, no foalsitter, no baby dragon... I couldn't have just made her leave. She needed a parent, and... I was happy to provide. Maybe too happy.
“A few years later, Twilight became my student. I was grateful when she took to Spike so. I hoped it was enough to have her live for someone else.”
“Wait,” Twilight Sparkle said. “So... all those study groups you made me join... all those group projects you put in my curriculum...”
“An attempt to fix my mistakes. I was disappointed when you only treated them as assignments. But then, you never seemed to care much for what was done with knowledge. You just wanted to learn because you loved learning.”
"So... how did she disappear through the mirror?” It was Pinkie who voiced what was on everypony’s mind since they heard what had occurred just a few hours before. “Where does it lead?"
"I'm not sure, Twilight. I only know this: it leads to another world."
Everypony started talking at one.
"Another world? Like in Granny Pie's stories?"
"Well, tarnation, I never would have figured..."
"But those stories with humans... they simply can't be true."
Celestia silenced them all. "I don't know the exact nature of where it is. It could very well be the world the humans came from. I wouldn't know. The stories were old when I was young."
"You mean you never checked what was on the other side?"
Celestia shook her head. "I have no clue where it leads. You know I wasn't always immortal, I assume?" Everypony nodded. While neither Princess announced that fact, they did little to hide it either. "When Luna and I took the throne after defeating Discord, we were gifted the mirror by an order of unicorns that had been doing everything to keep it safe. They explained that ponies going through it could greatly upset the balance."
"Balance?" Applejack asked.
"I can't explain it fully without giving you an hour long lecture in things you've never even heard of, but as a whole worlds like to remain separate. A pony or two traveling to other worlds will do nothing. But if too many do so, it could cause disaster. That is why I am sending Twilight through alone."
"What?" Twilight couldn't help but raise her voice.
"Then why the heck are we all down here?" Applejack demanded.
"Sunset knew too much. She knew about the Elements of Harmony even when she shouldn't have. She knew where Twilight was sleeping. She knew magic I didn't teach her. I'm afraid we must take into account the possibility that she has informants and allies still in Equestria."
There was silence for a moment.
“...The changelings?” Twilight ventured.
“It’s possible,” Celestia sighed. “And that’s what your friends will be doing. I need somepony to look into this while Twilight is busy retrieving her Element.”
“You’re sending me in? Me?” Twilight’s breathing grew more rapid. “Are you sure? Why not a member of the Royal Guard?”
“Because the Element of Magic chose you, Twilight. It trusted you for its safekeeping. That means you are the one most qualified to retrieve it. It knew you would rise to any challenge given to you.”
“I... I see.” Her voice was one of disappointment, like a foal who realized she wasn’t getting out of school. “When do I leave?”
“As soon as possible. You must go alone. Not even Spike may accompany you.”
“Um, excuse me,” Fluttershy said quietly. The rest turned to her. “Um, I understand why you’re sending Twilight to get her crown, but... why are you asking us to to find out who Sunset was working for?”
“When Olive Branch made his move, he had ponies in the guard on his side. I... I suppose he’s made me paranoid. I worry who in this castle is truly loyal to me. I need ponies I can trust.”
“We won’t let you down, Princess!” Rainbow Dash said, flying up and giving her Princess a salue.
Twilight sighed. “I guess I better go pack...”
“Nothing too much,” Celestia said. “Just a few references to the Elements, and some food. Nonperishable, save it if you can’t find any other food. And... I want you to be prepared to be gone for a while.”
Twilight blinked. “Why?”
“Well... this mirror only opens up once every thirty days. Once you step through, you won’t be able to come back for a month.”
Scootaloo hadn’t slept well. Not due to having to share a bed with Apple Bloom, she had done so often enough, but due to how annoying it was to have her plans cancelled on her like this.
Now she sat at the Apple family table, eating toast and breakfast hay, and being as determined as possible to be in a bad mood.
“Well, since you’re not gunna be busy today, maybe we can be Cutie Mark Crusader Skateboarders.”
“If you’re gunna be doin’ that, stay outta Doctor Whooves’s garden. He still gives me looks in the marketplace since ya crashed inta that fancy blue lawn ornament o’ his,” Granny Smith muttered.
“I guess,” Scootaloo said. While skateboarding was fun, she made sure it sounded like she was being forced into it.
“Come on, Scoots, it ain’t like Rainbow Dash does this a lot...”
“I know...” She still refused to be any less ornery. She poked at her plate a bit more before finally giving in and asking Apple Bloom, “Where would we be skating?”
“I hear there are some good ramps in the outer fields...”
“Oh no, ya don’t,” Granny Smith said. “That there’s too close to th’ Forest!”
“Aw, Granny, we ain’t gonna go in...”
“Timberwolves still might come out. They’d eat fillies like you in a single bite. You stay outta that area.”
“But all th’ supplies are there!”
“Big Mac can haul ‘em out fer ya.”
“Um, actually, Granny, I can’t. I promised Miss Cheerilee I’d help her with something at her place.”
Big Mac realized too late the torrent he had unleashed.
“Ya mean it worked? We got Miss Cheerilee a special somepony!”
“Whowee! Finally, great-granbabies! How quick’s it movin’? You best get a bun in her oven...”
“It ain’t like that,” Big Mac said. He didn’t speak loudly, but the slight strain he was putting on his voice was enough for anypony who knew him. “She just needs a few things fixed and I’m cheaper than any carpenter.”
There was a few seconds of disappointed silence.
“Well, what about that there Princess Luna? She was eye’n ya during the Summer Wrap Up.”
“...Granny,” he mumbled as his skin turned red, much to the amusement of the two fillies.
“Are you sure you have everything?”
Twilight would have chuckled at Spike having adopted her usual state of worrisome bother if she hadn’t been so nervous. “I have the reference books on the Elements, enough food for three days, and a few ingredients if I need to brew any of the potions that Zecora showed me. I think I’ll be okay.”
Twilight looked into the mirror, her own reflection just staring back at her. The others stood around. “I’m sorry to send you into this, Twilight, but it must be done.”
“I understand, Princess.”
“Besides, I’ll bet you beat ‘Sunshine’ in minutes and spend the next thirty days just laying around.” Rainbow Dash was wearing a grin that she usually reserved for talking about herself.
“Just remember, she’ll likely know everything you do. Be prepared for anything.”
Twilight nodded at her teacher’s words. She still didn’t move.
“We’ll miss you! When you get back, we’ll throw you the super biggest party ever!”
“Good luck, Twilight!”
“I’m sure you’ll do fine, Darling!”
Twilight wished she felt half as confident as her friends did. She took a deep breath and, before she could stop herself, she dashed through the mirror.
For a few moments, everypony was stunned by the surreal nature of Twilight’s disappearance, the mirror’s shimmering the only evidence she had ever been there.
Which is why nopony noticed Spike dashing toward the mirror until it was too late.