This was going to end badly. She could feel it in her bones. Her bones which didn't seem to like supporting her right now- She was shaking, hiding it as best she could. That basically meant being as quiet and unassuming as possible. Picture that in contrast to Celestia, striding with her confident and radiant (beauty) poise, her (flank) legs stepping in time with the movement of (Twilight's heart) the clocks on the street. Celestia, her mentor and guide, was walking ahead of her into a store that was almost tailor-made to create embarrassing or awkward situations. Twilight had heard Luna call her sister a prankster during the party, but never quite believed it... until now. Now she believed it all too much and was preparing herself for the worst. Not to mention, she had absolutely no idea how the shopkeeper would respond to royalty to begin with, much less royalty in this kind of mood.

It was a (minor) relief when they stepped into the small antechamber and the front door closed behind them without any incidents. She really shouldn't be this worried about something going wrong in the first four seconds, but, well... She knew Pinkie Pie. So her estimate of "time to disaster" was a bit on the paranoid side (which she preferred to think of as 'cautious'). And speaking of paranoid, she needed to find something else to fixate on or else she would have a T-word level breakdown. OK Twilight, you're going into a store. Just think about what they sell. All of those toys, and devices... all that art... those books... Alright maybe that was the wrong train of thought to be riding. (Mmmh) Ah, so, no talk of 'riding' either. Just... calm. Concentrate. You're Her student, you can do this. Probably.

The little eye-height door-- Alright, well, eye-height for her, maybe-- slid open and a sliver of a blue unicorn became visible on the other side.
"Good afternoon, and welcome to our shop! We just need to make a quick confirmation check that you aren't magically disguised or underage."

Celestia cleared her throat meaningfully, only to start with surprise when Matte laughed in reply.
"Yes, even you milady. Can never be too cautious."

"But you do know that it's very difficult to disguise oneself as an alicorn, correct?"

"Yes ma'am. But difficult doesn't mean impossible, just like impossible doesn't necessarily mean difficult. There are ways, I have been told. Anyway, you both check out clean-- Come on in!"

If Twilight had heard anypony else taking that kind of casual tone with her mentor, she would have been worried for them. But... Celestia laughed, really laughed in response, stepping inside ahead of her when the door opened. So instead of getting mad or scared, she smiled as well (forced, so forced, so nervous) and stepped inside.

She had honestly expected her second time inside of this shop to be easier. That was before she realized she would be coming inside with Celestia, thus giving every single item a new... context. Before, they had simply been intriguing toys and tools for use in solo experimentation. Now? Now she was picturing exactly how that black harness would slide onto her teacher’s flank, how that particular piece could be used on her, and she was blushing fiercely enough to singe her coat. It only got worse the more things she saw, and when her eyes flitted onto the racks of magazines and books, it got so much worse.

That was the point when she realized it had been about five seconds, and that she was not going to survive an entire visit. During her little blush-induced stupor, Celestia had already entered the store proper, eyeing the merchandise (and, thankfully, not the proprieter) with her usual regal poise. She looked from one shelf to another with a discerning gaze, eventually looking to Matte.

“Do you have anything in the way of, ahem, ‘plot devices’?”

Matte pointed her towards a particular section, and she went that way, Twilight following in confusion.
“Um, Princess, not to be a bother, but... Why would this kind of store have a literary trope in stock?”

“Oh Twilight, I don’t mean that kind of plot device. I mean the kind you use for filling plotholes.”

Twilight was still baffled. Well, she was baffled, until Celestia turned around with a particularly massive jet-black anal plug in her magical grasp, showing the sex toy to her student. Twilight’s brain had just barely managed to wrap itself around the idea that that was hypothetically capable of going inside of her, when Celestia spoke.

“Any thoughts on this specific model, my student?”

“I... Buh...”

“I’ll take that as an “It’s perfect”, then.”

She couldn’t object, because Celestia was already wheeling around with surprising speed, turning on her back hooves alone to face a different display. She perused the... um, false genitalia (She was still too flustered to even think the word ‘dildo’, much less whatever name the female equivalent had) with a look of intent studiousness on her face, the same kind of serious glare she had been earlier giving a rough-to-translate segment of a spellbook. Finally, she looked at the last of them and turned to Matte.

“Any personal suggestions?”

To his credit, Matte just smiled and nodded towards a separate shelf. Twilight turned to look and then went entirely stone cold. This was it. The moment that would end her sanity. Because on that shelf?

On that shelf, there were what seemed to be both kinds of ‘implement’, which is to say, false... um... parts. Female and male parts colored and modelled after specific ponies. Famous ones. Like, perhaps, both of the current customers? Oh yes, she was quite positive she saw the lavender shade of her own coat on one package; at the same time Celestia leaned forward and looked down at a white and gold one, with trimmings the color of an aurora. Her face scrunched up, and she turned to Twilight, who, in turn, prepared her final words.

“Princess, I-”

“Could they have at least asked for reference? This bears no resemblance to me! In all seriousness, just look at this!”
She levitated the package into Twilight’s face, who was struck by the simultaneous urge to back away in slight creeped-out-ed-ness and, at the same time, lean forward and do something unspeakably lewd herself. Stuck between the two options, she simply stammered and blushed and shook a little. Celestia shook her head again and put that one down with a sigh. Twilight watched in horror as her eyes flitted across the next row down, which she was entirely sure had a parodic label that was, in some way, a play on the title “Elements of Harmony”. She didn’t dare look, but it just felt like what would be done in that situation.

And she did not, in any way, walk over to inspect the one bearing her colors and mark. No. Nor did she shake her head sadly and agree with Celestia in regards to deplorable inaccuracy: That would be ridiculous, in the circumstances. So after they failed to share a glance and a chuckle, Twilight went back to panicking. Celestia went back to the shelves, now asking Matte several questions that Twilight did her absolute best to block out (while her subconscious took copious notes). Eventually, the shop-pony yelled back past the counter, to his wife:
“Mon amour, I could use a hand out here!”

“Coming right out, Matte.”

“If the two of you do not mind, I’m going to step into the back for a bit. You both seem like very trustworthy ponies, so I don’t have to worry, right?”

Celestia looked at him in confusion.
“...Haven’t you already had my student as a customer?”

“Actually, I can neither confirm nor deny that- We have an extremely strict privacy policy, Princess. So unless a prior customer was to reveal that fact themselves, or we were called on to aid in a criminal investigation, I could have had both of you as customers, and would never say a word.”

“That... Is actually quite wise of you. I approve.”

The following moment was one of awkward silence before Twilight spoke up.
“Yes. For the record, yes, I have been here before, and she already knows that.”

Matte smiled and started walking away.
“Then I can confirm that I trust both of you. Nickle will be out momentarily.”
And with that, he was gone, leaving Twilight and Celestia. Alone. In a shop full of... Oh dear.

“So, Twilight...”

The sound that left Twilight’s lips was most definitely not any kind of word, nor even intelligible or reproducible. It did, however, lead to Celestia bursting out into laughter, bright and calming. She walked close and placed a hoof on Twilight’s shoulder.
“Be calm, my student. If you do not want me to continue making my little jokes and jibes, all you must do is ask.”

“I... no. Just because all of this is new to me, doesn’t give me an excuse to back down from it. And plus, like you said, I’ve been here before. So go right ahead, Celestia: Do your worst.”
It took her a moment to realize what she had just said, and another to parse the horrifyingly wide grin on the Princess’ face. But despite that, she did not retract her statement- After all, if she couldn’t handle this, how could she ever even dream of a real relationship with her? How bad could it possibly be?

--------

They walked into the house, Fluttershy’s eyes cast to the floor as they reached the foyer. She offered to take Luna’s saddlebags, but the Princess simply shook her head and began to walk downstairs. Oh. Oh! She had to beat Luna downstairs but there was no room so she was going to beat her there and...

“...May I ask what has occurred in thy basement?”

Fluttershy leapt down the stairs, flaring her wings to slow down- A trick she would have been hard-pressed to pull off, two weeks ago- and landed right behind Luna. Before them was a cleanly-lit room, open space filled with a table, a couch, streamers, balloons... There was a covered platter of snacks, drinks, and all sorts of things. It looked like... Well, it looked like Hurricane Pinkie-Pie had just swept in and redecorated.
“A... well, I... MaybeItalkedtomyfriendsandtheysaidIshouldhaveaparty.”

Luna quirked her head to one side and, miraculously, figured out what she had ‘said’.
“A party? Whatever for?”

She scuffed one forehoof back and forth along the carpet, trying to look away but failing.
“...You. Visiting and everything. They thought that, um. It might help if we could ‘mingle’.”

"...I do apologize, dear Fluttershy, but is that term not meant for interacting with a... group? As opposed to just the two of us?"

"Well, yes. But... I'm, you know... shy."

At that, Luna smiled at her, and backed up to the couch before plopping down onto the cushions, curling her legs beneath her.
“In that case, I see merit in this idea. I am, as they say, “game”- What would you like to talk about?”

If she weren’t so breathless, she would sigh with relief. As it is, she decided to be a bit bold and join Luna on the couch, sitting next to her and nuzzling the snack tray open to retrieve a plate.
And they began to talk.

--------

Twilight had known it was going to be bad.
She had not, however, known how bad.
How bad?

Whispering.

That’s all she was doing. Celestia was simply whispering. Nothing more.
But she was doing it right next to Twilight, her body shockingly close, her words breathy, each one sending her ears twitching out of reflex. And the things she was saying... Twilight didn’t know whether to melt, cry, come, or possibly all three. Her self-control and desire to not ruin a potential relationship-- Not to mention the vastly-more-important relationship of student and teacher they already held-- was barely sufficient to stop her. So she held up under the assault, listening very closely, her brain doing a solid imitation of a recorder, picking up every hushed word and imitated moan for later ‘use’.

Finally, the torrid torrent of speech was cut off by Nickle’n’Dime, the store’s other proprietor, stepping out of the back and across the counter with a mischievous grin on her face.
“Princess Celestia, welcome to our establishment! And welcome back, Ms. Sparkle-- I’m glad to see you back so soon.”

“Thank you very much- I’m glad to be here, having heard quite a bit about it from my sister.”

“Yes, um... thank you.”
Twilight would have answered more clearly, but was still entirely too flustered for that. Instead, she began, slowly, to look around the rest of the store herself, finally relaxing enough to actually peruse the goods. The stock had not changed much since her last visit, but was either changed enough, or subtly re-arranged, to make it seem fresh and new like the first time. There was even a bookshelf she hadn’t noticed before, headlined with several copies of a rather dignified-looking tome on the history of sex in Equestria. She decided to give it a look-over, levitating it over while Nickle and Celestia conversed.

She was enjoying her read-through, studying each section in turn. It was well-written, with an author’s name she actually didn’t recognize (a rare occurrence indeed), and a series of intriguing illustrations. Art from all of the pony cultures across Equestria and its history, everything from woodcuts to murals... ‘Oh, a section on Canterlot court traditions!’ A minute later, the book fell out of her grasp and slammed onto the floor, prompting Celestia to turn towards her student in concern. The mare seemed confused at Twilight’s slack-jawed horror.
“Twilight? What’s the matter?”

“P-p-page... seventy-six.”

Celestia looked at the book, and frowned. She looked at the title, and groaned in exasperation. She opened the book to the page in question and apparently confirmed her fear. The alicorn turned to Twilight and put on her best comforting expression.
“Now, Twilight, being that I am the Princess of the Sun, there are certain... associations. And perhaps I was asked to be present in a few... images.”

“So that's you. That's a painting which you, really and truly, posed for.”
The Princess pursed her lips and nodded.

Twilight decided it was time to stop looking through the merchandise before she gave herself a heart attack... Although not until after she got another good look at page seventy-six.

--------

What felt like hours flew by like minutes, the two of them locked in rapt conversation, not over-excited, but simply... Quiet, mutually enjoying each other’s presence. They spoke of their pasts, and their pastimes, and their friends and family-- Luna having more of the latter than the former after her absence, an imbalance reversed when the six of them befriended her. Fluttershy felt much closer to Luna, and even felt... Brave. Well, maybe not brave, but bold. Willing to take a risk. So when the conversation hit a particular lull, she turned to speak to Luna once more.

“Um. Well. Luna, I-”
“Dear Fluttershy, there’s...”

They both paused, stared at one another, and then went into a fit of giggles. The laughter kept going, both of them shaking and holding their guts, until they finally slid back into their seats, much closer than when they had started. She stared at Luna, only an inch away now.

“W...were you going to say...”
“I think so. Yes, We were. And you...”
“Mmhmm.”

They could have said something, then. It seemed better, in the moment, to opt for a kiss, deeper than their previous efforts, and with more passion behind it- They cared for each other, mutually, and reveling in that fact was enough to make speech unneeded and unwanted. They only broke their kiss long enough to smile, eyes damp, at one another. Another kiss began immediately, and another, and another. Hooves wrapped around necks, bodies drew close, and the snack table was bumped away in a seemingly-impatient burst of telekinesis. They stayed together in that way for longer than either of them cared to guess. Or care, for that matter- They had, they were both entirely sure, nothing better to do. Nopony they would rather be with.

It was a very good thing to be sure of.