Pink Day (Or: The Open Secret of Pinkie Diane Pie)
When Spike didn't answer the door after the steady knocking passed the two-minute mark, lizard-brain annoyance dragged Twilight out of the book she'd been reading. Settling the bookmark neatly into place with a flow of violet magic, the alicorn set her book down and trotted to the front door, wondering who it could be that was so insistent.
If it was a pony looking for a book, they usually just came right in and either found it themselves, or got help from Spike or Twilight herself. Was it somepony trying to sell something? Twilight grimaced at the thought as she trotted downstairs. She'd given in to the earth pony who sold helmets - and apparently triggered some kind of avalanche, as no less than five different salesponies had stopped by the library since then. She had only needed one helmet, Twilight grumbled. Not five of them, or a new sofa, or alligator proofing for the library...
Opening the door, the purple alicorn had to duck a hoof, tumbling onto her rump in the process. Fortunately or not, the hoof was at least a familiar one; the pink earth pony connected to it was humming happily as she rhythmically thumped at where the door had been with a back hoof.
"Uh, Pinkie?", ventured Twilight, standing up a little farther back than where she'd landed - just in case. "Hi. The door's open now."
Hearing her friends' voice jolted Pinkie out of her repeating motion with a squeal that was familiar to all of Ponyville as she whirled around, pressing a box into Twilight's surprised hooves. "Oooh, Twilight! I was wondering if you were home, here, I have something for you - well, for everyone but this one's for you and I know you're gonna like it 'cause I like it and actually Rarity helped me make one and I think she knows I made hers but I'm pretty sure she'll still act surprised, what do you think?"
Twilight blinked and slid her gaze from the grinning pony to the box, bright lavender wrapping paper as peppy as her smiling friend. "I'm sure she'll like it. ...Whatever it is.", she added, shaking the box gently.
"Aren't you gonna open it?", pressed Pinkie, leaning forward, snout bumping Twilights' gently as she widened her eyes.
"I will, but what's it for? My birthday isn't for --"
"Months! I know.", supplied the other mare.
"Right. And there's no holiday today...well, not any that's celebrated in Equestria.", Twilight continued, nodding.
"It's White Day, duh! Geez, Twilight, don't you have a calender?" Pinkie Pie darted past Twilight into the library - Twilight followed at a slower pace, unsurprised when the other mare pulled a calendar out what Twilight had been sure was a pile of old magic textbooks. She was equally unsurprised, if a little impressed, that the day was circled. Some things you just got used to, being around the party pony so much.
"White Day? That's not for another month! It's still February...", she protested, confused and insistant. "Hearts and Hooves Day isn't even for another two weeks."
"I know that, silly. It's an early White Day present! Now, I've gotta go deliver the rest of these presents - bye, Twilight! Catch you later!", Pinkie explained, darting out of the door in the same breath.
Twilight blinked at the sudden emptiness of the room. "Bye?"
"What was that about?" Twilight asked herself, glancing at the still-unopened present for the fifth time. She just couldn't keep her mind on her book, and she had told Pinkie Pie she would open her present... Surely the Voynich Manuscript could wait another couple of minutes, she decided, rolling herself off of her bed.
Tearing open the wrapping paper with delicacy - the carefulness she used had always annoyed her brother, when they were foals - Twilight opened the box and pulled out a folded paper representation of herself. Pinkie knew origami? The thought was amusing - it certainly wouldn't be the strangest thing her pink friend had knowledge about - until Twilight remembered that she'd mentioned getting help from Rarity with her presents.
The small origami figure was made from paper almost the exact shade of Twilights' fur; the bits of paper used her her mane and tail had been painted, she discovered, touching the paper mane with her hoof. The whole thing was delicate and small, only a few inches big, but able to stand up - it had all four legs so she didn't have to prop it against anything. It even - the bookish mare discovered, leaning closer to inspect her suspicion - had her Cutie Mark. Delicacy of that measure was almost definitely Rarity, Twilight thought to herself. Pinkie was good with broad strokes, and a party animal, but if somepony wanted something done with attention to patterns and detail, Rarity was the pony to ask.
So it would be Rarity she would go to first, to make sure their boisterious friend hadn't been acting off; not anymore than usual, at least.
But she really did want to look at the manuscript some more...
Then again, if something was going on with Pinkie, she owed it to her friend, didn't she? Of course she did; Pinkie Pie would have done the same thing for her if she thought there was something wrong.
Scowling at the moral mire she'd thought herself into - she never used to have this problem in Canterlot - Twilight sighed and closed the book carefully, floating it over to her desk and wrapping it back up gently. She would track down Rarity, see if Pinkie was having some kind of lack-of-party withdrawal that they should be worried about, and then - if nothing was the matter - she could come back home and curl up with a book and no worries.
Author's Note
The Voynich Manuscript is an actual thing, and a scholar like Twilight would no doubt want to take a crack at deciphering it.