"What do you mean, 'you're a Princess now?' "

"I mean, 'You're a princess now,' Twilight," Celestia said, repeating herself. "The title, the tiara, the royal authority, the whole regal magilla. You... are now... a Princess.... of the land... of Equestria." She tapped her former student on the nose with each pause for emphasis.

She had to repeat herself a bit loudly. An overexcited Nyx was all but bouncing off the walls of the library, shouting "yesyesyesyesyes" over and over again as she ricocheted around.

"But on what--- oh confound it. Spike, take Nyx someplace, will you?--Take her to Sugarcube Corner to celebrate. We need to talk here!" Twilight shoved some bits in Spike's claws and pushed him towards the exuberant filly's latest approximate location.

Spike looked confused. "But it's the middle of the night!"

Twilight started to facehoof, but Pinkie Pie jumped in. "No problemaroonie! I'll just open up the kitchen and have Nyxie help me bake your "congratulations on becoming an alicorn and a princess all on the same night!" Cake!" She pondered. "Boy, I'd better make it a jumbo sheet cake. That's a lot of letters to write in icing...."

"Fine great good perfect," Twilight said, pushing Nyx, Pinkie and Spike out the door. "Have fun!" She shut the door behind them not with a slam, but darned close to it. "Now--" She turned to face the Princesses. (The other Princesses? Was that correct now?) and realized that the rest of her friends were still seated around the library, staring at her. Right. The room had seemed sort of crowded... Twilight facehoofed.

"Don't bother tryin' ta shoo us along too, Twi," Applejack said with a wink. "We're here for the duration."

"Yeah, and anyway you'll just have to tell us everything over again later," Rainbow Dash pointed out from her perch on a freestanding bookshelf. Twilight sighed; they were right. But mission accomplished, at least; having both a giddy filly and a free-ranging Pinkie Pie in the room  would have made sane conversation impossible. She sighed and sat back down on her cushion facing Celestia and Luna.

"Okay, Like I was saying... you said I'm a Princess, Princess. Um."

"Just call me Celestia from now on, Twilight," Celestia said with a grin. "Otherwise that's going to get very tiresome."

"RRright. Anyway....I'm a Princess now?"

"Yes," Celestia and Luna nodded.

The Sisters were beings several thousands of years old, and had seen and heard just about everything. So it says something that Twilight's next question surprised them.

"On what grounds?"

Celestia and Luna blinked at her, then blinked at each other. Then blinked at her again. "Thou art an alicorn now, Twilight," Luna said matter-of-factly. "Thou hast ascended. Tis the natural order of things."

Twilight gaped at them. "Wait. What? Just because I grew these," she flapped her new wings for emphasis, "I'm suddenly qualified to rule a country? That's it?"

"Not just anypony is suited for ascendance, Twilight," Luna said, chiding. "They must needs take a throne--"

"Why did you make me of all ponies an alicorn, if that's the case?" Twilight said, getting to her feet in agitation.

Celestia chuckled. "I think you have misunderstood what has happened here today, Twilight," she said. "I didn't make you an alicorn."

"What you do mean? I finished Starswirl's spell, got transported to that starry-cloud-space dimension thingy where you were, you told me how proud you were of me and then you transformed me for--- what. No?" She paused as Celestia shook her head. "You didn't transform me?" Twilight asked hesitantly. Celestia shook her head. "It... was something else?" Twilight concluded. Celestia nodded.

"I thought it was the Elements that did it," Fluttershy said, pointing to the rather obvious scorch mark still visible on the floor.

"You know, I kinda knew Twilight was just gonna become an alicorn someday anyway," Dash said. At the skeptical looks she received she protested, "Hey, I did! I mean come on, she was uber mondo magical even before she was an alicorn. And her cutie mark story-- zowie! I figured she was like, a, I dunno, alicorn caterpillar or something," she finished with a shrug.

"Actually, it's a little bit of all three things," Celestia confessed. "You see, some very rare ponies are born with the... call it the potential to become an alicorn. If all goes well, when they reach a certain point in their development they 'ascend' to that dimension that you experienced, Twilight, where they complete their metamorphosis. It happened to Cadence quite shortly after her birth--- gave her mother quite the fright, let me tell you."

"Twould have been a great deal more exciting for her mother if it happened before her birth," Luna said wryly.

"Indeed it would have," Celestia said, half-chuckling. "Poor Mom. She never did let us forget, did she?

"Anyhow, there are certain things that can help a developing pre-alicorn along. And which are necessary for other reasons. Things like early training in magic.  Or exposure to certain powerful magic artifacts..."

"Like the Elements," Rarity said, eyes shining.

Celestia nodded. "In fact, we believe that one of the functions of the Elements was to act as tools for the ascendence of alicorns," she said. "After all, the most common effect of their power, it could be said, is to restore the true nature of a thing. To bring it back into harmony with itself, as it were."

"Like when they turned Nightmare Moon back into Princess Luna," Twilight said in a rush of insight. "Or restored Ponyville after Discord messed it all up."

"Exactly," Celestia said with a smile. "Starswirl the Bearded's last spell was meant to trigger that transformative attribute under, ah, more controlled and nurturing circumstances." She looked at the other bearers briefly, a tiny frown on her face. "Although we were expecting..." she tapped her chin with a hoof.

"What, Princess?"

"...Oh, nothing," Celestia said. "Nothing to be concerned about. Some other things we were expecting, but apparently the time is not ripe yet." She looked back at Twilight and smiled. "All in due time.

"Where was I? Oh yes. The reason you saw me in that aetherial plane, Twilight, is that we-- and now you-- are connected to it. We can move to it when we wish; we can also sense when something ascends to that dimension. I felt the magical eruption when you arrived there--- you made quite a splash, by the way--" Twilight blushed-- "So I went there immediately so I could, well, watch over the final phase of your transformation. I feared you might panic and injure yourself.

"Also, to give you that one last push to finish the transformation." She winked. "It's rather similar to birthing a foal in that way. It can happen on its own but it's still better to have a midwife there."

"Well that still doesn't answer the question of why I have to be a princess," Twilight said. She was getting a tad irritated.

"We thought we already said this," Luna said, a smidge exasperated. " Thou art an alicorn, and alicorns are rulers!"

"That doesn't mean a thing--" Twilight said heatedly.

Celestia waved a hoof between the two glaring alicorns. "Please, calm down, Twilight," she said in a soothing tone, trying to keep the peace. "My sister isn't explaining it well."

Twilight pouted a bit, but she lay back down. "I'm listening," she said.

"Twilight, Alicorns are immensely powerful. All else being equal, an order of magnitude more powerful than the next most powerful unicorn. Likewise swifter on the wing than any pegasus and stronger than any earth pony. And do you remember that old saying by Clover the Clever about power?"

"Power gathers power unto itself," Twilight recited. "What are you saying?"

"I'm saying that, whether an alicorn wants to be a powerful ruler or leader or not, they end up becoming one." Celestia said wearily."Ponies will defer to us. They will ask for our help in matters great and small. They will revere us and look up to us as examples, regard us as paragons whether we are or not. Place us in positions of power and authority. Do things in our name, because they think it is what we want. Whether out of love or out of respect or out of fear, ponies will follow us, simply because we are so powerful. Even if we never had you coroneted, ponies would place a crown on your head.

Worse, some ponies would try to use you as a means to power-- to start a war, or a secession, or even a coup. Or even start a cult..." Celestia and Luna both shivered as ancient memories flitted across their minds' eyes. "Far better to make you a princess the moment you ascend, control the proceedings, than to leave all those loose ends lashing about."

"You swore to Nyx and I that we wouldn't be sucked into this," Twilight Sparkle said, her voice thick with feelings of betrayal. "That you would keep us out of the politics and intrigue-- let us set our own course and our own lives--"

Celestia's kind, patient, regretful tone never changed. "And I'm saying to you now, that your ascension has changed all that," she said. "It was difficult enough keeping the machinations of the court from dragging you in before, when you were just my faithful student. It became monstrously difficult when Nyx came along. Now-- it's just simply impossible."

"Well what if she hid?" Rarity pointed out. "Fled to some far off island someplace or--- oh not that we'd want you to leave, Darling, we'd miss you and Nyx terribly--" she said to Twilight. "But if it came to it, if she just went off to live in seclusion, away from all... what? What is so funny?" For at the moment she'd said the words 'live in seclusion,' Celestia and Luna had shot each other a look and burst into hysterical laughter.

"I'm sorry, I'm sorry," Celestia said, wiping her eyes with her fetlock. "But when you said--" she giggled wildly, finally smothering it.

"I know it's a tad melodramatic..." Rarity said, miffed.

"It's not that, dear," Celestia said. "How do you think Canterlot got started in the first place?" At Rarity's bemused blink, Celestia explained. "After my sister was banished to the moon, I was in a pretty bad place. I left. Just flew off one day, found the highest mountain in the land, built a little cabin way up on top, and settled down to raise the sun and moon from there in peace and quiet.

"Within a week the Pegasi had built a cloud palace for me around the peak. Within a fortnight the first earth pony and unicorn stonemasons had laid the foundation..." she sighed and rolled her eyes. "I just gave up at that point."

"Twas nothing compared to when we first took the crowns," Luna said. " Or mayhap we should say had them forced upon us."

"Really? They forced you to become Princesses?" Twilight said, incredulous.

"Strewth," Luna said. "We never intended to claim the crown. But once we defeated Discord, the three tribes were at the door of our cottage shouting hail to their new Queens..."

"Oh my. What did you do?" Fluttershy asked.

"Ran like a couple of bucking chickens," Celestia said drolly. "--For two or three hundred years. Every time we found some new quiet little place to stay, within a decade ponies would be making treks to our front door, building shrines to us, swearing lifelong fealty..."

"The final straw wast the Everfree," Luna said. "We finally fled to the heart of the deepest, darkest, scariest, most dangerous monster-filled forest in all the land. We went to the cave of the Tree of Harmony and made refuge there. We sealed the cave, and cast a spell of deepest sleep upon ourselves, and there in that chamber did lie down side by side, to sleep for centuries, till a time when we judged ponykind would have surely forgotten us."

"And?" Twilight pressed. She and the girls were leaning forward, hanging on every word.

"And we woke up and they'd found us and the Tree, and built a bedamned castle right overtop us while we slept," Luna said sourly.

"You should have heard Luna swear when we woke up and saw the palace," Celestia said. "I think she invented half the profanities ponies use today, right then and there."  Luna blushed, but didn't deny it.

"So you're saying... that there's no way out of this, is there?" Twilight said sadly. Her ears and wings drooped; she was the picture of despondency.

Celestia's smile became sympathetic. "I'm afraid not, Twilight," she said. "Ponies are going to want you to be a princess, one way or another."

"So what now?" Twilight said.

"Now? The coronation, in Canterlot," Luna said. "Then some few months of work as we set you in your place as the newest Princess of Equestria. Establish your royal authority and position, some public appearances and speaking engagements, carving your niche with the noble families and the peerage, determining your royal duties, establishing your entourage, arranging some courtly training... I'm sure Pomp and Circumstance (1) would help with that..."

"You'll be moving back into the palace, of course," Celestia said. "For the immediate future. Until we can make more proper arrangements..."

Celestia and Luna noted how Twilight's eyes grew more glazed with each addition to the list, and they shared a small, enigmatic smile with one another. Luna flashed a thought to her sister through the mental link they shared. I do feel bad for her, but---Do you think it will work?

Celestia's small smile widened just slightly. Oh yes. She took careful note of the tiny twitch in her former pupil's eye. Spectacularly.

1)Luna's redoubtable majordomos. One was a unicorn, one was a pegasus. And otherwise indistinguishable from one another-- even their cutie marks were identical.