“So I’m sure you’re all wondering why I’ve called you here today.”

Twilight paced across the lab, in front of a wall full of charts and graphs and incomprehensible equations. She was wearing a lab coat, for no reason other than the air of authority it gave her, even if only in her head.

The rest of her friends were in various states of lounging across the room, half of them on desks for a lack of chairs. Sunset was the only one who seemed to really be paying attention, though the eager expression on her face made it clear that it was mostly because she was expecting a good story.

“So,” Twilight began, ignoring the fact that Rarity was on her phone, and Applejack and Rainbow Dash were still in the middle of whatever conversation they’d been having when they walked in. “As you all know, more and more Equestrian magic has been leaking into our world, and it has a tendency to become dangerously unstable if not properly contained, such as in our geodes.” She pulled out a laser pointer and used it to point to one of the diagrams on the wall behind her, which was incomprensible to anyone but herself, but did have a nice picture of a gemstone on it.

“I’ve been trying to study the effects of Equestrian magic on our world, but I don’t have any good samples. Our geodes are too important to mess with, and every other source of magic we’ve found has been abused to the point of forcing us to get rid of it. So I think it’s high time we went straight to the source.”

Sunset sat up, eyes widening as she realized where this thread was going.

Twilight shone her pointer onto a second diagram. “We need a source of magic from Equestria itself. Something we can bring back and monitor. I propose we go through the portal, sneak into Celestia’s castle, and steal Christmas.”

“What.” Rainbow Dash spoke up, apparently having at least been paying attention to the last sentence. “You can’t steal Christmas. Haven’t you seen The Grinch?”

Twilight shook her head. “You can’t steal Christmas here. But Equestrian magic is based on concepts like friendship, and harmony. Over there, Christmas—”

“Hearth’s Warming.”

Twilight paused. “What?”

“Hearth’s Warming,” Sunset repeated. “It’s called Hearth’s Warming in Equestria.”

Twilight blinked. “Hearth’s Warming, then. It’s a source of power there, just like loyalty, or kindness.” She waved a hand at Sunset. “Tell them I’m right.”

Sunset frowned, thinking. “Well, the original Hearth’s Warming unfroze Equestria, united the tribes, and drove off the Windigos, so… yeah, I’d say there’s some power there. Don’t you think they’d notice if Hearth’s Warming went missing, though?”

Twilight shrugged. “They’d probably just recreate it with the power of friendship or something. Besides, they’re constantly throwing magical artifacts they don’t want into our world. Least they can do is let us take one we want to study.”

Everyone was paying attention now. Fluttershy had shrunk down in her chair, hands over her mouth, and Rarity was looking thoughtful. Applejack was the one who spoke up, though. “I’m not sure I’m too comfortable stealin’ anything from Celestia. Ain’t she a literal goddess over there? You’re asking ta get smote.”

Sunset rolled her eyes. “She’s not that kind of goddess. Celestia hasn’t smote anybody since before Luna was banished. At worst, she’d give us a friendship lesson.” She turned back to Twilight. “This sounds awesome. I’m in.”

“Me too!” Rainbow was quick to add. “I’ve always wanted to be in a heist.”

“Hee hee! This’ll be fun!” Pinkie added.

With a majority on board, Twilight smiled. “Alright, then. Here’s the plan…”

Sunset was the first through the portal. She was the most experienced in being a pony, and the least likely to cause any suspicion if she ran into anypony on the other side. She quickly scoped out the portal chamber, but it was empty. Once she was sure she was alone, she took a bit out of her saddlebag and flicked it into the portal, as a signal that everything was clear.

Rainbow Dash was the next one through, adjusting to a four-legged stance with greater ease than the last time she’d been here. And not a moment too soon, as she was able to catch Applejack as she stepped through and immediately fell over.

The others followed in quick succession. Fluttershy stared at her hooves in abject fascination, while Pinkie Pie bounced around the room like she’d been born on four legs. Rarity similarly took the time to admire her new form, seeming much more appreciative than Fluttershy, and Twilight came through last, settling comfortably into a four-legged stance.

“Everyone adjusting?” Twilight asked, her gaze scanning over the forms of her friends, familiar and yet so very different.

“Everypony,” Sunset corrected. “Give them a minute or two, it can be pretty disorienting.”

Twilight nodded. “Everypony,” she agreed, even though infiltration wasn’t part of her role. After all, it would be difficult to pass as an alicorn princess when she lacked the full set of limbs required. “We can’t stay here long if we want to get to Canterlot without a full welcome party.”

Sunset nodded. “Everypony ready?” she asked the room. “Brace yourselves, then. I’m a bit rusty.” Her horn lit up, and a red glow surrounded the group of ponies. Sunset strained, sparks arcing from her horn, and then there was a pop and a flash and they vanished.

The door opened, and a purple alicorn poked her head in. “Hello?” she asked, frowning at the empty room. “I could’ve sworn…”

The group piled onto the train, a bundle of giggles. “Oh man, that was priceless,” Sunset gasped out. “Way too close, though.”

“Man, did you see Applejack’s face?” Rainbow asked. She looked to the orange pony across from her and clarified, “Other Applejack, I mean.”

“I got that,” the apple pony drawled. “And I can’t say as I can blame her. I’d be mighty spooked too, if I didn’t already know what was going on.”

Twilight gestured with one hoof, guiding the rest of the group into an empty train car. “Hopefully, she won’t mention it to other Twilight anytime soon. She’d be able to work out what was happening, and we can’t afford those kinds of complications. At least we have less chance of running into ourselves now that we’re out of Ponyville, though.”

She gave everyone a moment to settle onto a train bench—it took a little longer than she’d have liked, but then again, for half of their number this was their first time dealing with the wrong number of legs. “Now that we’ve got a bit of time to ourselves, we can confirm a few things. Rarity, do you want to do the honors?”

Rarity glanced over, and then nodded. She held up one hoof and concentrated. Her horn lit up, and a shimmering array of hexagonal gems appeared in front of her. “It would appear our geodes still function,” Rarity said easily, setting the formation spinning in midair.

Twilight gasped softly, and nudged Sunset. “Look, look!” she hissed, waving a hoof at Rarity’s horn.

Sunset looked between the two of them oddly. “What?” she asked. “We’ve all seen Rarity’s magic before.”

Twilight shook her head. “No, not that, her horn! It glowed when she used her geode! That confirms my theory!”

Rarity tilted her head, angling the gemstones to use them as a mirror. “My horn?” she asked, looking curiously at the appendage. “Oh, so it is. How strange.”

Sunset still looked nonplussed. “I don’t see how this matters. She’s a unicorn, of course her horn glows when she uses magic.”

Twilight shook her head. “Her own magic. If the magic was solely coming from the geode, her horn wouldn’t be a part of it. It’s channeled through her. That means the magic is a part of us. It’s why we can use these gems, even though everyone else seems to go nuts the moment they come across an Equestrian artifact.”

Sunset’s eyes widened in understanding. “Oh. Oh. You’re right.” She smiled, and without warning, nuzzled into Twilight. “I can see why that might be an important distinction,” she murmured, for her ears only.

Twilight blushed, but didn’t pull away. “Anyway. Ahem. Thank you, Rarity. We’ve still got a lot more work to do, though.”

To her relief, the others got to work without commenting.

Sunset watched the guard post carefully, hidden in the bushes. Even from the outside, castle security seemed to have been enhanced since the last time she’d been here. She’d been sent alone to do recon, and find out just what kind of defenses they’d need to overcome. All she needed to do was find one of the guards on his own. So she watched and waited for one of them to neglect the buddy system for a single crucial moment.

It didn’t take all that long. One of the guards said something to his compatriots, and then stepped away from the castle and towards Canterlot proper. Silently, Sunset trailed him until he was out of sight of his fellows. Only then did she approach. “Hey, stranger,” she called, striking a pose. She still remembered how to be sexy as a pony, right?

The guard turned, and Sunset flipped her hair and smiled at him. “Uh, hi,” he said, bemused. “Can I help you?”

Sunset fluttered her eyelashes at him, and took a few steps closer. “I don’t know, handsome. Can you?”

He frowned. “I’m not sure what you mean. Do you need directions?”

Sunset let out an aggravated sigh. “Yes. Directions,” she deadpanned, dropping the sultry undertones from her voice. “Can you tell me where I might find a clue?”

“I don’t under—”

Sunset wasn’t listening. While the guard considered, she stepped up to him and reached out a hoof to touch his shoulder. Her eyes flashed white, and memories spun through her head. A moment later, she pulled away. “That was super helpful, thanks!” she informed him, and then teleported away before the confused guard could respond.

Twilight had picked a park on the outskirts of Canterlot as a reasonable base of operations for everypony to get a chance to stretch their legs and practice being a pony before the main event. She’d cleared it of snow, and was practicing more complex telekinesis when Sunset returned. “How’d it go?”

Sunset flopped down onto the wet grass. “Ugh. Fine. I got the info we needed.”

“You don’t sound happy about it,” Twilight observed.

Sunset rolled over onto her back. “Twilight, am I a sexy pony?”

Twilight sputtered, dropping the snowballs she was juggling. “W-w-what??”

If Sunset noticed Twilight’s shock, she didn’t acknowledge it. “I tried to seduce a guard and he didn’t even notice! I may not have paid enough attention to stallions when I was Celestia’s student but I always assumed I could get one if I ever wanted to, y’know?”

“Sunset, I’m not sure if this is the thing you should be focusing on right now.”

“Right.” Sunset frowned. “You’re right. I’m being silly. We should talk about the defenses.”

She sat up, and looked around. Rarity had built an intricate display of interwoven gemstones that resembled a giant snowflake. Pinkie Pie was hopping merrily from snowbank to snowbank, throwing explosive confetti into them at random and giggling. Applejack was lying on the ground nearby, hat dipped low over her eyes, and Fluttershy was having a quiet conversation with a pair of snow rabbits as a trio of birds busied themselves braiding her mane. “I see training went well.”

Twilight nodded. “We should be ready to take on anything they throw at us.”

Sunset lit her horn, and spread out a patch of snow like a canvas, drawing a diagram into it. “They use their badges as key cards. You need them to enter here, here, or here. I figure swiping one should be relatively easy. There’s also blocked off entrances here and here, which Applejack or Pinkie should be able to breach.

“They have fans to prevent flying nearby, but we probably weren’t going to do that anyway, unless Rainbow got the hang of it…” Sunset paused. “Where is Rainbow, anyway?”

Twilight pointed up. “She got the hang of it.”

Sunset looked up. “I don’t see—”

There was a whoop and a rainbow contrail blazed its way across the sky, turning on a dime before resolving itself into Rainbow Dash, laughing maniacally. “Oh man, and I thought superspeed was awesome on the ground!” she exulted. “Let me at ‘em, I could steal the whole castle!” She looked down. “Oh hey Sunset. What’s the plan?”

Sunset blinked. “Right. Well, Rainbow can deal with the fans if she wants to, I guess. Anyway, the real problem is the anti-magic field they’ve got inside the castle. We won’t be able to teleport in, and our geodes probably won’t work either. But if we can avoid the guards, we should be fine.”

After a moment she added, “Oh, and they’ve got geese guarding the throne room. I… don’t know who thought that was a good idea. Fluttershy, can you take care of that?”

Fluttershy looked up, and then turned as one of the birds in her mane chirped. “Oh, you know these geese?” she asked quietly. “Well, could you go tell them that I’d like to talk to them, please?” The bird chirped assent. “Thank you ever so much.”

Sunset grinned. “I’ll consider that dealt with, then.”

Twilight looked over the diagram. “Is that it?” she asked. “It seems kind of… lackluster.”

Sunset shrugged. “Well, it’s more than what they had last time I was here.”

Twilight nodded. “Alright. Two groups, then. Sunset, you take Applejack, Pinkie, and Fluttershy in through the tunnels. Rarity, Rainbow, and I will steal a badge and go in through the front door. We meet back up at the throne room.”

“What if one team don’t make it?” Applejack spoke up.

“Don’t wait up for them. Getting out with the target is the first priority. Ponies don’t tend to shoot first. If anyone gets caught, it should be easier to rescue them later than do a second shot at the heist.”

Sunset nodded. “Let’s do it.”

Sunset had expected something to go wrong. After all, it couldn’t really be true that the pony capital’s defenses were so easily bested, could it? She was almost disappointed when Fluttershy was trivially able to occupy the singular guard’s attention long enough for Applejack and Pinkie to demolish the bricked up tunnel entrance. The labyrinth of tunnels was supposed to be a maze, but the guards had all been drilled in its layout, and thus, by proxy, so had Sunset.

Before she knew it, they were under the throne room. Fluttershy flew up, had a brief conversation with the geese, and then brought the rest of them up one at a time. Sunset took a brief look around, but didn’t see any signs of the other group. Surely they would be along shortly, though. “Good work, Fluttershy,” she murmured, looking up at the geese who were watching them with curiosity but no alarm. “The vault should be just behind the thrones.”

She pulled aside the curtain, and there it was, set into the wall. The massive metal doors gleamed, and in the center was a circular slot, just the right size for a horn. Sunset considered it. “I’ve seen a lock like this before. The key is a specific spell, easy to cast but impossible to guess.” She ran one hoof across the metal. “Surely she’s changed it since I was banished…”

With a slight shrug, Sunset lowered her head and inserted her horn into the hole. There was a brief flare of red, and a click. Then, ponderously, the vault door swung open.

Sunset gaped. “You’ve got to be kidding me. I went mad with power! How could she not have changed the locks?”

“Maybe she didn’t think you’d come back?” Fluttershy suggested meekly.

“Maybe ponies are just really bad at security, and she just plain forgot,” Applejack added.

“Maybe it’s just a plot device to progress the story!” Pinkie offered cheerily.

Sunset blinked at her.

“Or not,” Pinkie added, unperturbed.

Sunset stepped into the vault, her eyes scanning over the shelves full of all manner of fantastical artifacts. She stepped up to the ornate purple box in the center of the room, hoof hovering just above it. But then she sighed and lowered her hoof. Even if it was the Elements, she didn’t need them anymore.

“Sure you don’t want to just take a peek?” a teasing voice asked from behind her.

Sunset turned to find Twilight, Rarity, and Rainbow Dash standing in the entrance. “You made it!”

Twilight nodded, taking a step forward. “It wasn’t hard.” She gestured to the box with a hoof. “I thought the Elements were all you needed to take over Equestria,” she said playfully. “That’s them, isn’t it?”

Sunset glared. “I don’t want to take over Equestria,” she shot back. “And I have definitely put my raging she-demon days behind me.”

Twilight smirked. “Well, it could have been fun.”

“I didn’t sign up to take over Equestria,” Applejack drawled, reminding the two of them that there were other ponies in the room.

“Yes, we’re not dressed for it,” Rarity added. “We’d need significantly more black.”

“She was kidding, girls,” Sunset muttered. “C’mon, let’s find the thing we’re actually here for.”

“Is this it?” Rainbow’s voice carried from deeper inside the vault. The rest of them followed her voice around a corner, and then they all stopped, as one.

Before them was a crackling fire, burning without smoke or any apparent fuel. A circle of stones surrounded it, each one perfectly smooth and evenly spaced.

“It’s a literal hearth,” Twilight muttered. “Of course it is. I don’t know what else I should have expected.”

“Um… how are we going to take it?” Fluttershy murmured.

Twilight touched her chin briefly. “Rarity, do you think you could make a platform for it?”

“I can try, darling.” Rarity’s horn flared, and a thin hexagon blossomed under the fire and the circle of stones. A moment later, it slowly lifted off the ground. Rarity wobbled slightly, clearly struggling, and then Twilight’s pink aura surrounded the gem platform, taking some of the load.

“Alright, let’s get out of here before anypony notices,” Sunset announced, turning to head back to the throne room.

When she stepped out, she stopped, a sudden feeling of unease washing over her. Then, one of the thrones slowly spun around. Sitting on it, staring regally down at Sunset, was Celestia herself. “I’m disappointed in you, Sunset,” she intoned, her voice booming but not quite into Royal Canterlot levels.

Sunset took a moment to put two and two together. “It was a trap,” she finally whispered. “You left the key the same as bait.”

Celestia nodded. “Very good. I assume you have already learned that the Elements no longer reside in this vault. Did you find any of the lesser artifacts to your liking?”

Sunset gulped. So she had been tempted by an empty box. That was nice to know. She took a brief look behind her, and was relieved to find that her friends were wisely staying out of view. Her mind raced for a way to keep them out of trouble. Finally, she settled on the obvious. She drew herself up, settling on a haughty expression. “You’ll have to catch me to find out,” she announced, before bolting across the throne room. Once she left the vault, she would be back in the anti-magic field, and hopefully she would take Celestia by surprise.

No such luck. She felt the tug as Celestia’s magic encased her in its golden glow, and struggled to no avail. “What… the anti-magic—”

Celestia chuckled. “I would hardly install an anti-magic system that I didn’t have a way around, don’t you think?” she asked gently. “Now, talk to me. I thought we had reconciled. Why would you break into the vault?”

Sunset’s gaze flicked to the open door again. She still needed to get Celestia away if her friends were going to escape. She opened her mouth—-

“It was my idea!”

Celestia’s gaze snapped to the vault, and her jaw dropped. “Twilight?” she asked incredulously. But her shock only lasted for a moment as she took in the glasses and the lack of wings. “No… not my Twilight. What is going on here?”

Sunset winced. “I had it under control!” she protested.

Twilight hmphed. “Sure, and what kind of friend would I be if I just stood there and let you sacrifice yourself, hmm?” she shot back, ignoring Celestia.

“Oh come on, Celestia wouldn’t hurt me. I think.”

“Then she won’t hurt me, either. And it was my plan. I should take the blame.”

“You shouldn’t—”

“Girls!” Celestia cut in, exasperated and not used to being ignored. “I’m not going to hurt either of you. Would someone please explain what is going on here?”

There was a moment of silence. And then, with a deep breath, Twilight explained.

“I told you it was a bad idea,” Fluttershy murmured.

“Eh, it all worked out, didn’t it?” Rainbow replied, taking another slice of cake. “Any plan that ends in cake is a success in my book.”

“I’m still not sure this is entirely fair,” Rarity added, though she didn’t put down her own slice of cake. Turning to Celestia, she added, “Don’t you think this seems a bit… harsh?”

Celestia smiled. “Oh, I’m sure they’ll be fine. Once they’ve learned their lesson, I’ll let them stop.”

On the other side of the room, on two enormous blackboards, Twilight and Sunset were each writing “I Will Not Steal Hearth’s Warming” five hundred times.