The two pulled up to the front of the school just before the arrival of dawn. Sunset parked off the curb and Twilight carried the construction supplies they had loaded into the trunk. Half an hour later they had a sales stand set up, two meters tall and just as wide, right next to the still-shattered statue.
Twilight staked a sign into the grass and straightened it.
Cookies!
6/1$
16/2$
She walked over to where Sunset was loading boxes of cookies out behind the stand, "It was really nice of Pinkie to make us all these cookies."
Sunset smiled, "I just asked her for four thousand cookies. They were in my car by the end of the day. She never asked what they were for."
Twilight inspected Sunset's work. Sunset had constructed a wall of cookie boxes that blocked off a third wall with the stand and the mirror. No-one from the street would be able to see anything they did around the portal.
"Are you sure this is going to work? It violates fundamental conservation of energy! I mean, the output the portal would have to produce to generate new matter in sufficient supply to-"
"I'm sure. We've talked this circle before, Twilight. It's equestrian magic. It doesn't work the same as standard physics. Just be glad it does. The cookies certainly aren't going to pay for that lab of yours."
Twilight set up her station, just in case anyone actually wanted to buy any cookies. Assuming anyone drove by the school at all six days before Christmas. She started to turn around, before thinking better and snapped back forward, "Are you ready back there? Do you need anything else?"
Sunset checked over their visual barrier one more time, "I'm fine. Thanks. I can get started now."
After one last sweep of their defenses, Sunset quickly stripped off her clothes. The brisk winter winds brushed her skin. She shivered.
Twilight almost turned around again, "Are you ok?"
Sunset rubbed her hands on her arms and nodded vigorously, "Yeah. I've just never been outdoors in winter without hair or clothing before. It's cold."
Just then a young man in a cashmere coat walked up to the stand.
Twilight turned her attention to the unexpected complication, "Hello sir. Would you like to buy some cookies?"
Sunset braced herself for the portal shock and stepped through.
The customer answered in a Scottish accent, "Isn't it a little late in the year for you to still be at school?"
Twilight kept up her smile, "Yes, yes it is. The school just seemed like such a prime location to set up my stand."
The two individuals glanced around briefly at the street. Besides themselves, not a soul occupied any line of sight they could choose.
The man turned back, "Yes, quite so."
Twilight wondered why she hadn't heard Sunset come back through yet.
Sunset Shimmer arrived on the other side of the mirror. She allowed herself a moment to smile at the familiarity of her pony body. Four legs, a tail, and most importantly a horn that let her feel the magic of the world around her.
"Sunset?"
The pony in question instantly looked up to see what - no - who had made the noise. She saw Princess Twilight Sparkle. She sat, and stared. And then she sat some more.
"What are you doing in Equestria? Is there something wrong at CHS?"
Sunset stood up on four legs, "No, nothing's wrong."
There was a pause as Twilight waited for the response to finish.
"Not that I'm complaining, but why are you here then? You don't usually come through for personal matters."
Sunset recovered from the last of her shock, "You're right. I don't. I was just coming through to... conduct an experiment I thought of that requires magic."
The princess grinned, "Oh! Well don't let me stop you. I was just reading the works of Hippo Cratese. Father of the modern healing charm, and all that. You know he and his daughter ended the Hippopotamid-Draconic War a thousand years ago? Quite a fascinating story, really."
Sunset sat back down and readied herself for several minutes of hearing the story.
"...and the griffons were forced to mediate between the factions while Cratese was free to go save the dragons who had been captured by Lord Pygmy...
"...But the griffons had actually hidden inside the siege weapon so that when it was stolen from the alliance camp, they could know exactly where the dragons had been keeping their army..."
Look, if Sunset was being entirely honest, she only listened to the first thirty seconds. She'd already read hippopotamus history. And if she was being entirely honest, she had considered just bolting back through the portal without explanation over a dozen times by this point. But she also knew that she was still a former enemy of Equestria. She knew what had happened with Discord and Tirek and knew that she couldn't afford to act suspicious.
"Hey, Twi?"
The alicorn stopped, "Yeah?"
Sunset smiled apologetically, "I've got to get back to earth."
Twilight nodded, "Oh of course. I'm sorry. But, wait... what about your experiment?"
Sunset blinked, "Right. The experiment I came here to perform. You know what? I forgot one of the ingredients back in my car. Give me just a minute. You go ahead and get back to your reading."
Twilight yawned, "Now that you mention it, it is getting a bit late. I should hit the hay. I'll visit again soon, ok?"
"Sure. I'll look forward to it. Night."
Twilight left. Just as Sunset was about to return through the portal, she realized how odd it was that it was night in Equestria now when it was still morning at CHS. Mystery for another time, she supposed.
When she arrived back at the cookie stand, Sunset was wearing a full set of clothes, just as she had predicted. She looked down and confirmed that her old set of clothes was still lying in the grass next to the mirror.
She heard a man's voice from in front of the stand, "Did you hear that?"
Twilight had in fact heard Sunset return, "Hear what, Mr. Smith?"
The Scottish man tried to look past her into the back of the stand, "I thought I heard a whooosh. Did you hear a whooosh?"
Twilight shook her head, "No, Mr. Smith. I most certainly did not hear a whooosh."
Sunset began to strip down again. She noted that these clothes were different from the ones she had come through with the first time. It would be interesting to find out if it was random or if there was a pattern to it. She jumped back through just as the cold started to get to her.
The customer grinned at Twilight, "Please, call me John. Only my daughter calls me Mister Smith."
Twilight strained to keep up her own smile, "Right then. So, John, did you want to buy any cookies? We have chocolate, spicy chocolate, vanilla carrot, coco choco, mystery nut, and regular."
John Smith leaned back and bounced on his heels, "Are there any nuts in the mystery nut? I just recently became very allergic."
A whooosh sounded from behind the stand.
Twilight gritted her teeth slightly, "The mystery nut cookies do have nuts actually. I think the coco choco and vanilla carrot may also have nuts."
Whooosh.
Mister Smith scratched his chin, "So that leaves chocolate, spicy chocolate, and regular?"
Whooosh.
"Or the fire surprise variety pack, which contains mostly chocolate with a few spicy chocolate scattered randomly."
Whooosh.
"Oh that is brilliant! Who came up with that? I'll take a dozen boxes of those."
Whooosh.
Twilight turned carefully toward the wall of boxes, without facing the mirror as to allow Sunset some degree of decency, "Is that the sixteen for two box?"
Sunset, meanwhile, was staying as close to the mirror and as low down as she could to avoid being seen through the currently unobstructed counter window. She scooped up all the copies of clothing she could reach as well.
"Yes please. You can never have too many cookies. A cookie saved my life once, actually."
When Twilight turned back to the counter, there was a very naked Sunset hiding in the corner holding a pile of skirts and tops and bras. She calmly placed the boxes on the counter, "Here you are. A dozen boxes of fire surprise."
Sunset dropped her pile of clothes and darted back through the portal.
John stopped counting bills abruptly, "Ok, seriously. What's that sound? You can't have missed it that time."
Whooosh.
"Maybe it's the wind?"
John shook his head, "I was a weather analyst for fifteen years and I never heard wind that sounded like that."
Whooosh.
"There it is again! Do you know what it sounds like to me?"
"What's that?"
Whooosh.
"A portal."
Twilight froze.
"You know, like in the Valve game? Aperture Science. GLaDOS?"
"I've never played it."
Whooosh.
"There it is again. Did you hear it?"
Whooosh.
"One of life's great mysteries I suppose."
Twilight spotted a lone piece of underwear rolling across the pavement behind Mister Smith.
The man picked up his purchases and started to turn away, "Alright. I'll see you around probably, eventually. Have a nice day."
Whooosh.
"Would you like a bag for those?"
"Yes, thank you that would be-" Whooosh "-Hey Twilight I think we should..."
The three stood there in silence for several seconds.
Twilight broke the ice, "John, this is Sunset Shimmer, my... assistant."
Sunset waved through the window.
Mister Smith set his boxes back down and nodded in greeting, "Assistant... really. So what does she do?"
Twilight and Sunset spoke simultaniously,
"Sorry?"
"Sorry?"
"I mean no offense, it's just Twilight mans the counter. Twilight manages the stock. Twilight handles the money. So, Sunset, what do you do?"
Sunset's eyes flicked over to the massive wall of boxes she had built, "I... baked the cookies. I hope you like them."
He outreached for a handshake with a huge grin, "Always a pleasure. Was the variety pack your idea? Because that's just brilliant! I love it!"
She took his hand and then was shaken enough to immediately regret it, "Yes. It was. It was my idea. Yes it was. I'm glad you liked it." She looked around her for inspiration again, "I thought of it while I was taking my clothes off."
She cursed the large pile of discarded fabric at her feet.
John Smith looked at her like she had just said something just as awkward as what she had just said.
Twilight handed him a paper bag, "Thank you for coming. I hope to see you here again soon."
He took the chance to end the silence gladly, "Thank you. I think I probably will come here again."
The two girls watched to make sure that the man walked all the way away and rounded the corner out of sight. Then the watched the corner for several more seconds just to make sure he was really gone. Then Twilight kept watching for a while more.
Sunset got back to work.
Whooosh.