Twilight, as much as a surprise this must be, was in a library. More specifically, the Legal wing of the Canterlot archives. Her route was a shortcut to the Biology wing exit that she had never used before, oddly enough, but finally she decided that her fellow Princesses could stand to accept her company on the East balcony (the doorway to which was next to the exit of the library) exactly 46.3 seconds before 5:30 AM officially began, instead of exactly 5:30 AM. The clock on the far wall from Twilight read 5:41 AM and normal circumstances would dictate a panic attack only Twilight would be capable of producing.
[/[spoiler][/spoiler]b]But these were not normal circumstances. This was an emergency. A meeting on Twilight's capacity for military leadership could wait.
Since her ascent to the biological marvel of Alicorn, her senses had become sharper, to the point that she could spy, for example, dirt on the crystal floors of her castle that no other living species could, to the dismay of a certain lizard, detect without UV lights. This was her first time visiting the legal wing post-evolution. And she spied a horrible and intolerable secret that had laid undisturbed for nearly 1400 years. There was a missing decree.
At first, turning into the wing, Twilight was focused on her upcoming meeting with her fellow monarchs and the five highest ranking military commanders in service, three of which brought themselves out of retirement to guide the young and innocent protege of Celestia in the ways of war. At the end of the wing, she turned to the right and saw, at the very bottom left of the gargantuan bookshelf, decree 2,604,231. The scroll, embroidered in violet cotton ribbons, was the official document accepting Twilight Sparkle as an Equestrian Princess. More relevant, printed underneath, was its number. Twilight froze in place as her blood chilled. In the back of her mind, a primal fear roared. It can't be… a math error? Twilight thought, not daring to speak her theory aloud.
Step one: recheck the data. One, two, three…. Her pupils were a blur as, in the interest of time, Twilight did not look at the individual numbers, sacrificing cognitive function for speed. Because brains work that way. Two million, six hundred and four thousand, two hundred twenty nine, two million, six hundred and four thousand, two hundred thirty…. “Oh fuck,” Princess Twilight proclaimed.
Step two: identify the problem. One, two, three…. She spent twelve minutes before discovering a discrepancy in the style of the scrolls on which the decrees are recorded. She returned to the first of these oddballs. Most of the scrolls were put on neat, thick parchment, sealed with silk rope and housed upon cherry wood. This one, however, was a piece of thin paper folded over hayburger style. Curiosity held Twilight, and while she definitely wanted to find the error in her sanctuary, she rationalized that background knowledge would benefit her search in time. She carefully pulled the thin paper from it’s shelf and opened the magical preservation seal (because magic) and read:
Decree 3,682:
If anyone sees that damn blue thing that keeps following the royal convoy yelling, “Sissy!” or some shit, don't feed it, it might go away.
Twilight finally realized just how powerful she had become as an Alicorn, for after seconds of stunned silence, she realized her jaw was still attached to her head. But Celestia referring to Princess Luna like that? No. This is another error. I need more data points. She flew to another piece of paper, this one crumpled and torn but put under the same enchantment as every other scroll, so this trauma happened before it was accepted as Royal law. Twilight took a deep breath and unrolled the paper:
Decree 3,942:
Somepony teach Luna how to say her name. She knows how to pronounce ‘L’s so she must just be trying to be cute. Also, if she gets the children's potty seat around her neck again, don't help her out of it. She needs to learn.
A blush and a giggling fit grounded Twilight, imagining Princess Luna, formerly known as Nightmare Moon after being hailed as the goddess of war in nearly equal measure with the night, as a little filly in near tears asking for help with a potty seat clashing with her tiara. Her fear subsided and, in realization that this might just be the best day of her life, forgot about her meeting. She charged her magic and soon had turned a nearby table into a monument to Luna’s filly years. And there were a lot of them.
Decree 4,252:
Awards of merit or honor are reserved for living beings; imaginary friends cannot be recognized in these ceremonies.
Decree 6,712:
If anypony is told to stop chewing on her mane, that does not give that pony the right to chew anypony else's just because one is seen as royalty.
Decree 12,309
Any castle constructed to house both myself and Princess Luna shall have the Royal bedrooms in two towers opposite from each other with at least 200 steps in the stairway. Also, if Luna says there is something under her bed and the teleports under it yelling, “it’s me!” again, she will lose her royal status. Cute stops at midnight.
By this point Twilight was crying with laughter. As she tried to fight to see another parchment doctrine concerning Luna’s habit of blowing bubbles in her soup, a melodic tone made itself known.
“Princess Twilight, might I ask why you are amusing yourself in a library when you are nearly 30 minutes late to a meeting concerning your ability as royalty?” The form of Princess Celestia dominated the wing of her library, with Luna not far behind.
Twilight bowed her head so fast it nearly broke the sound barrier, “I’m so sorry, Princess! I was on my way there and I- um, Princess?” Celestia had walked past Twilight and picked up one of the scrolls. She began laughing just as Twilight had done, losing all composure. Ripping it from her sister's telekinetic grasp, Luna read:
Decree 8,430
It shall be known to all that Alicorns are capable of sitting on their haunches and do not need to spend any time upside down when on a throne.
Luna's blush burned brighter that her sister's sun as she said, “If We are not mistaken, there is a meeting that requires our presence.” Angrily motioning for Twilight to follow her with her wing, she trotted back up through the Legal wing. Twilight's brain began to work again.
“Oh! Wait, Princess, I think there is a missing scroll! I… stopped looking after a while but-,”
Stealing a quick glance up at her right, Luna said with a smirk, “Ah, yes. Decree 55,412-” Celestia stopped laughing, “my first. Anypony who decides to eat four whole cakes cannot complain to her sister about the size of her plot. Also, anypony that insists on wearing multicolored leg-warmers and headbands in public shall forfeit her royal authority.” Twilight was staring at a mortally embarrassed Celestia as Luna added, “T’was the very look that killed disco.”