"It's not even my best side"
"Oh, it's a good day to be alive, for sure!" Luna trilled, waltzing care-freely down the corridors of the almost unforgivably immense Canterlot Castle. [Narrator: Some say the castle is bigger on the inside, but it's just a vicious rumour spread by the Cult of Chrysalis.] And she wasn't wrong - the sun was shining brightly, the gentle summer's breeze was wafting along the ever-so-slightly-drafty hallways, and birdsong could be heard through the open bay windows. The Princess of the Night had just awoken from a peaceful, almost dreamless night at the proverbial coal face, and for once actually felt somewhat refreshed.
As she trotted, chipper as can be, down to breakfast - winking cheekily at the scandalised guards, whistling merrily at random and with no attempt at a tune, and generally passing on her good cheer to all and sundry - she wondered what her sister Celestia could have planned for the morning meal. Breakfast in that cavernous hall was not usually Luna's favourite meal, being as it were right at the end of a gruelling shift when all she wanted was peace and quiet, and she generally had the same thing each time - but today she felt in the mood for something other than coffee and walnut cake with a stiff brandy.
Poking her nose in at the kitchens, she bellowed at the cooks with her good-natured Royal Canterlot Voice: "Good morning, one and all! No cake for me today, I shall have whatever my esteemed sister is having!" And so saying, she made a rapid exit, leaving several hard-working ponies blinking stars from their eyes and rubbing the deafness from their ears.
After several further minutes of cavorting, dancing, whistling and general merry-making [Narrator: The castle really is enormous. I'm beginning to wonder if there's something in that cultist nonsense.], she finally arrived at the dining hall, bursting in with a grin on her face, a smile in her heart, and with the joy that only someone who has slept well and long can express. "Hello, hello, hello, my dearest sister! How goes it with you on this finest of mornings?"
And what a sight met her glowing eyes. Celestia was sitting, hunched, at the far end of the room, staring at the tablecloth and fiddling with her napkin.
Undeterred, Luna cleared her throat - perhaps Celestia hadn't seen her - and tried again. "Hello there, dear sister! How goes it with you on this finest of mornings?"
In response all she received was a faint hmm.
Feeling just ever-so-slightly deflated, but nonetheless attempting to continue her merriment, Luna pranced lightly over to her sister, looked her in the eye, and asked: "Everything alright, Celly old girl?"
The Princess of the Sun blinked, and broathe [Narrator: breathed?] in sharply. "Oh, Luna dear - I'm sorry, I didn't see you come in."
This seemed a trifle unlikely to Luna, given the ruckus she'd been making all the way there, and the particularly energetic way in which her entrance had caused the double doors to connect with the wall, but she didn't argue. Instead, sensing a sister in need, she plumped herself down on a comfortable cushion, and inquired: "Something on your mind, Celly?"
After taking a moment to gather her thoughts, Celestia nodded. "Well - yes, actually. But it's alright, I know you've had a busy night; you must be tired. You don't need me bothering you as well."
Putting on her best the-doctor-will-see-you-now face, Luna shook her head firmly. "Not at all, dearest sister. I've had a peaceful night, and I want to help you feel as refreshed as I feel! Now tell me, what's on your mind?"
Celestia sighed. "Alright then, if you insist."
More encouraging nodding from Luna.
"Well - it's like this", Celestia began. "Twilight has been writing to me faithfully every day for the past two years."
More nodding - Luna was very familiar with what she considered to be the height of helicopter princessing (not that she'd ever said so; she knew how fond Celly was of her favourite student). "Go on, sis."
"You see - well, sometimes I get the impression that she doesn't really care. As in, she's happy to send me a letter each and every day - she's almost fanatical about it, actually. But although she writes to me every day, she never seems to reply."
Not quite understanding, Luna tilted her head to one side, in that manner of hers which had made so many young admirers weak at the knees over the past couple of years. "Come again?"
"Every day she sends me a letter. And every following morning I send one back. But the next day she never even references my letter. It's like I've not sent one at all. And sometimes - sometimes I wonder if she's moving on. That she doesn't need me anymore, or that she doesn't care. But I don't know! And she has replied occasionally, so I don't know if I'm expecting too much, or. . ."
As she trailed off, Luna marshalled her thoughts. "So, to clarify: You're saying that Twilight doesn't always reply - in fact she rarely does - and you wonder why you bother writing to her every day?"
This time it was Celestia's turn to nod.
Luna frowned in reflection. This didn't sound like the Twilight she knew. Young Miss Sparkle was known for being reliable to the point of obsessiveness over just about everything, and writing was surely no different. "When was the last time you sent a letter which Twilight definitely replied to directly?"
"Oh, I don't remember. It's been so long. Before the Grand Galloping Gala, I think."
"When you sent her the tickets?"
"That's right - at least, I think that was it", Celestia pondered, before adding: "But sometimes she makes it sounds like a don't write to her often enough - here, listen to this, from her letter yesterday: Dear Princess Celestia, blah blah blah, friendship is important, yada yada. Here we are. It would be lovely to hear from you more often - I miss our fireside chats. Your loyal student, so on and so forth."
Again, Luna frowned. "And she says something like that quite often?"
"I would say most of her letters suggest I'm not writing often enough - at least half of them."
"Right. . ." An idea was beginning to form. "How does Twilight send her letters to you?"
Not sure why it mattered, Celestia looked confused. "I though you knew. . ? She sends them magically, using Spike's fire-breath."
"And how do you send your letters to her? Because we don't have a dragon here to do it for us."
Wondering where this line of questioning was going, Celestia shook her head. "No, we don't, so I use my own magic. But I can't use that method very often, because I have to draw the power from the sun instead of from fire-glands, and it's pretty draining for both me and the sun. So I tend to send letters that way only if I need a reply urgently, and in the evenings or at night when the sun will have time to recuperate before the morning."
"I see." Luna nodded in understanding, before posing a further question: "So what do you do normally, then - when it's not urgent?"
"I just use the regular Equestrian Postal Service. If it's good enough for my little ponies, it's good enough for me!" She smiled benignly at the thought of her many millions of subjects, all using the ancient EPS. Which they had to, because she had banned postal competition. [Narrator: Why? A story for another time.]
Luna - who at some point during the conversation had felt, and fulfilled, the urge to wear a dear-stalker and smoke a pipe, felt that she was beginning to get somewhere. "So you use fire-magic if it's urgent, and the EPS if it's not. And does Twilight generally reply to your urgent letters?"
Still feeling a little unsure, Celestia nodded again. "Yes, I suppose so."
"Okay, next question. This might seem odd, but bear with me. How do you post a letter?"
Somewhat surprised, but glad to have an empathetic ear, the elder sister went through the process. "Well, first I put the letter into an envelope, and lick it shut. Then I write Twilight's address on the front, and post it."
"You post them yourself? No-one else sees these letters?"
"Yes. . . and no? I go for a walk every morning, and post them myself in the postbox on Letsby Avenue." Celestia was beginning to look confused.
Luna took pity on her, and smiled benevolently upon her dear, upper class, slightly-removed-from-society-at-large sister. "I think I might know why Twilight doesn't seem to reply to most of your letters."
Her sister raised an aristocratic eyebrow, and uttered a single monosyllable: "Oh?"
Smiling inwardly, and struggling to hide a chuckle, Luna asked one final, fatal question: "Have you ever put a stamp on your letters?"
More confusion; the eyebrow rose further. "Stamp? Why would I stamp on them?"
"No no, 'Tia darling. Not stamp as in 'stamp on something'. A stamp."
Eyebrow reaching new heights. "I beg your pardon?"
Luna facehooved - mostly to hide a grin which she suspected would not be taken in good humour. "Celly! Come on, surely you, of all ponies, knows what a stamp is?"
Both eyebrows this time, accompanied by a what-the-hay-are-you-on-about squint. "What the hay are you on about, Luna?"
Taking a deep breath, Luna managed to compose herself. "Celestia. Sister dear. A stamp is a little sticker that goes on the front of a letter, to show that the postage has been paid for. If it doesn't have a stamp, it won't get delivered."
"WHAT?"
Wincing at the Royal Canterlot Voice coming from one with even larger lungs than herself, Luna nodded fervently. "I'm sorry, 'Tia, but if you've been sending letters without stamps, the EPS won't have been delivering them. Twilight never replied because she never even received them!"
Celestia blinked in shock, her eyebrows by this point bordering on stratospheric. "But, but - show me!"
Fortunately the morning's post to the castle had already been brought up by the staff, so Luna was able to lean across the table (which was still barren of food - perhaps the kitchenmaids are afraid to come in with 'Tia in such a state?, Luna wondered) and grab a letter addressed to herself. "Here", she said, pointing at the little green sticker in the top right corner. "That's a stamp."
The Princess of the Sun grasped the letter in her magic and brought it close to her eyes. "But that's just a tiny picture of my face", she murmured.
"Indeed. The postal service is run in your name, so all stamps must have your likeness on them somewhere. Come on Celly, this is basic stuff!" Luna tittered.
Celestia slumped back in her chair. "So you're saying that none of my hundreds of letters have even been delivered!?"
"I'm afraid so, sis."
The archprincess muttered, and grumbled, and grouched, and finally spat out: "It's not even my best side!"
Luna couldn't supress a chortle at that one, and was about to reply before being cut off again. "Celly, y'know you - "
"But where are they all?"
"All what?"
"All those hours I spent writing. . . Where are all my letters now?"
Luna considered. "Well - normally if a letter is sent without a stamp, the delivery office will keep hold of it until they can get hold of the sender. But if you didn't write a return address on the back, they'll just keep hold of them indefinitely, or until the intended recipient collects them in person."
Celestia stood up, eyes gleaming with rage. "I shall change this! I shall see to it that all my letters are delivered this morning!" Then, without further ado, she galloped from the room.
Well, thought Luna to herself, as the kitchen staff started appearing timidly from various doorways they had evidently been eavesdropping from, and started to lay breakfast out on the table, that was an experience.
Later that morning, many miles away in a quiet corner of Ponyville, there came a knock at the door of the Golden Oak Library. As Twilight was wrapped up in a book, Spike volunteered to answer. "No worries Twilight, I'll get it!"
The young dragon scooted eagerly down the beautifully carven stairs, paused briefly to swoosh back his spines - you never know, it could be Rarity coming to call - and pulled open the heavy oaken door; what he saw made him quiver. "Er, Twilight? I think you'd better get down here. . ."
In a flash - quite literally - Twilight appeared on the step next to her faithful assistant-cum-adopted brother. "What appears to be the problem, Spike? Oh, my. . !"
A large, bristled, frowning post-stallion stood imposingly in front of the doorway, blocking the sunlight with his vast frame. He was a unicorn of few words. "You Twilight Millicent Sparkle?"
Twilight gulped. "Erm - yes?"
The stallion made a note on his clipboard. "I've got eight-hundred-and-fourteen letters and fifty-five parcels here for you, delivered today by order of Princess Celestia herself."
Twilight was about to speak, but the unicorn - after consulting his clipboard again - interrupted.
"Oh - and they're all postage due."
Twilight gulped.