They went back the next day, teleporting just outside the library and walking in. Twilight picked up where she'd left off. Robert abandoned his research and dove into the medical texts.

“All the doctors that have examined Scootaloo, you'd think they'd have noticed something.” Twilight said, in response to his chosen direction.

“Bah.” was Robert's particularly articulate response. "If they were capable of doing their jobs, we wouldn't be here.” he elaborated.

“I must ask you to be quiet.” a librarian snapped, appearing Pinkie style said.

“She says, talking louder than either of us.” Robert said to Twilight. "Never mind that we're also amidst a personal privacy spell so as to not disturb other patrons.”

“I've never known Princess Luna to have much respect for privacy spells.” Twilight noted. Lunabrarian deflated and sat down on the bench, disguise vanishing.

“How didst thou know?” Luna asked, accent slipping slightly. Old habits were hard to break, but she had made progress. Still disappointment made her less careful.

“I know of no librarian who can afford silver shoes.” Twilight pointed out. Luna flushed.

“Oh. I should have thought of that.” she said with a sigh.

“Don't worry, you'll remember next time.” Twilight said. "So what has you up so late?”

“I noticed the two of you up late last night, and while I am glad someone appreciates the night, I was wondering what had you awake then that has you back now?” she said. The change in tone finally made Robert's jaw, which had been hanging open from the moment of Twilight's reveal snap shut.

“Princess.” Robert bowed his head. Luna bowed back.

“Please, call me Luna.” Robert's jaw worked for a moment, then a blank look came over him. A small, but insistent buzzing noise came from his ear. Luna looked at Twilight.

“He's been hanging out with Pinkie Pie.” Twilight said. Luna nodded. She helped many ponies conquer their nightmares, but she avoided Pinkie's dreams. There was only one pony who could help with Luna's nightmares and she was still embarrassed to explain what caused them after she peered into Pinkie's dreams. Though she was fairly certain that the circumstances were as much a cause as the image of Big Mac in a French maid's outfit.

“I understand.” Luna said, and shuddered.

“Anyway, we're looking for a spell to see magic.” Twilight said.

“Why do you need a spell?” Luna's horn glowed a moment. "Is not magic readily visible?”

“When I cast it, yes, but not the magic inherent in each of us. Luna raised an eyebrow. A friend of mine, a small Pegasus, named Scootaloo?” Luna nodded in recognition. "She can't fly, and we think there might be something wrong with her magic. We've been trying to find a spell that will let us see it, but no luck so far.”

“Ah.” Luna sat back, tapping her chin with her hoof. "Why does he have wings?” she asked, noticing them for the first time.

“Magical accident with a potion.” Twilight replied, not paying more than casual attention as she read.

“I see.” Luna glanced at Twilight, and then at the still softly buzzing tiger. She reached up, lifted the top of his head, and then let it fall. The buzzing cut off with a click, and he looked around.

“Oh, hello Luna.” Robert blinked. "What were we talking about?”

“Twilight was telling me you needed to find a spell to see magic.” Luna said.

“Must have zoned out for a moment. Heard of anything like that?” Robert asked hopefully. He might not be the best researcher ever. He was pretty sure Twilight had that title locked up. But he was hell on wheels with a shortcut. Luna shook her head. Worth a shot.

“I did miss a thousand years of magical development. You might look in the archives.” she suggested.

“Archives?” Robert asked. Twilight was still wrapped up in her book.

“Yes, the library Archives. Where they keep the books either too fragile for distribution, or the books too specialized to need a permanent place in the stacks.” Luna glanced at Twilight. "Would you like to look Twilight?”

“No, I've been down there.” Twilight said. "I'd rather search up here. You're welcome to go if you want.” She turned the page. The other two looked at each other. Twilight was not known for turning down a chance to do research. The book must have been fascinating.

“Follow me.” Luna said, standing and leading Robert away. Twilight watched them go, and smiled. She turned back to her book. Daring Do was just leaving the death trap.

---

Luna led the way into the archives, horn glowing softly. There were only a few books in here sensitive to light and the librarians assured here that they were contained within magically shielded cases. They wouldn't be bothered by it. She was glad. Like Twilight she did not approve of the destruction of any knowledge. The filing in the oldest of the archives was frankly atrocious and she was quite certain that Twilight would have torn great sheaves of her mane out. She could, Celestia had assured her, repair such damage easily. It was one of the first spells the white Alicorn had taught her sister upon her return. Twilight and Luna shared a love of, and natural ineptitude for alchemy. Translated into laymen's terms, they tended to blow hair off at any provocation. Celestia had pointed out that they were not alone, and that she had commissioned the creation of a spell to deal with such disasters sometime after Luna's banishment.

Of course, Luna had objected to the suggestion that she was inept, but Celestia pointed out a few embarrassing incidents. Fortunately, chemistry fared far better in their hooves, but still it was a useful spell to know. Luna couldn't count the number of times she'd lost her eyebrows even doing simple research. A thousand years prior she'd spent an entire month with no facial hair at all, before she successfully worked out how to stabilize gunpowder. Of course, that also meant that twice per day Celestia laughed herself into a breathless fit.

The archives were enormous, even by the standards of the palace and library above them. They were more than a mile down in the mountain, further down than the crystal mines, further than the old tunnels carved when such defensive measures were still needed. Like the library in Ponyville, the roots of the Canterlot Royal Library ran deep. The shelves were elderly here, and cut off from the rest of the library by a huge chain fence. The head librarian had given Luna the key. And a page of safety precautions. Books on magic, the kind of magic that deserved to be locked up securely, were often the dangerous sort. And they tended to react to magic in a bad way. There was a second gate further ahead. It was made of glass, with a glass mechanism, and there was a glass key, kept in a safe place that would open it. Beyond it lay the most potent magical tomes ever created, good and evil, kept in individual safes that kept them contained. And glass though it was, Luna was certain, absolutely, unequivocally certain, that nothing, not even the entirety of the mountain being lifted into the skies, and thrown with all the might of any pony capable of lifting it, against that glass, that it would hold even against that mighty and terrific blow. She had made it herself. And what she made, nothing could destroy. Nothing but her. Even her sister, who kept the key could destroy the vault, though she could without issue destroy everything within it. The vault itself would survive even unto the end of the world on which Equestria rested. A grim smile came to her as she thought that it would be the last remnant of her and her sister, after her sister's sun destroyed the planet, the vault would fly away into space.

But that wasn't where they were headed. She turned a corner, and examined the signage.”Here we are.”

“Magical innovations?” Robert asked. "Why are they down here?”

“For one, no one wants an Earth Pony accidentally turning in a unicorn. Again.” Luna said. It had happened a few times, before they were able to track down the book causing it. "While there's an incantation to reverse it, most of them have no idea how to control the magic, and go a little mad with power.”

“Ah.” Robert said, not fully understanding, but getting the gist.

“Let's see...” she reached up and carefully extracted a slim volume from between two much heftier tomes. Robert skimmed the titles, and wondered what could be kept between 'Anecdotes of Improv', and 'Annals of Milquetoast the Magnificent'.

“Here we are.” Luna laid the book on the table. It was open, and there words on it. This was the sum of Robert's capabilities.

“It's in ancient equestrian.” Robert pointed out. “And I don't read it. I can speak a bit, but I can't understand anything written.”

“Oh. Right.” Luna disappeared in a flash of light. When she reappeared a moment later, Robert was under the table, and the books were going mad. One smacked Luna in the back of the head. It flipped over and smashed into her horn. “AGH”. The Canterlot voice rang out. The books heard it and turned. Twilight's horn flared, just once. A wall of water gushed down around the entire area. Magic flashed and failed. The books dropped. Robert extracted himself from under the table, and took hold of Luna.

“Princess?” he asked.

“We asked you to call us Luna.” she said. "However, we will forgive you this once.”

“LUNA?” Celestia called as she appeared just outside the section. The water flow cut off from a flash of her horn. Several librarians appeared. "What happened?”

“Princess Luna teleported me down here to look at a book, and some of these went wild.” Twilight said.

“Sister? I thought Teleportation was an internal magic?” Luna said, rubbing her head, as Robert helped her up. "The paper said nothing about it.” she held up the paper she'd been given. It did say no powerful external magic, including telekinesis.

“Normally that is true sister, unless one carries another with them.” Celestia gently reminded her. For a long moment, it appeared as though Celestia had raised her sister. Luna's radiant face faded slowly, and her head hung.

“How could I forget the most important of tenets?” she asked. Celestia laid a wing around her.

“Worry not dear sister. No harm was done.” Celestia looked to Twilight. "Exceptionally quick thinking.” Twilight smiled.

“It's not the first time I've had to do that.” she said, slightly sheepishly. Luna looked up. "You're not the first pony to forget about teleporting another being.” Celestia laughed suddenly.

“Oh, I remember. I had most of this area in my throne room for a while.” Luna looked at her sister. "Twilight came here with Spike, forgetting the rule. He found himself forced to defend her until the librarians could trigger the water to cut off the magic. The only flame he could muster was the one which sent things to me. How surprised I was to find myself being assaulted by books.” she laughed again. "Did you find what you were looking for?” she asked.

“I believe so sister.” Luna explained things with help from Twilight, and Robert. She showed her sister the book.

“Hmm...” Celestia skimmed the book. "I'm pretty sure this is not it.” Her poker face would have made most card players fold, and possibly run screaming.

“How can you be sure sister?” Luna asked.

“And though she looked hungrily upon his magic wand, she resisted the urge to polish it ere he gave unto her his permission.” Celestia intoned sonorously. Twilight... sparkled. She was very nearly glowing in the dark. Luna seemed confused for a long moment. Robert? He applauded softly.

“The most magnificent reading of erotica I have heard in some time.” Luna nearly fell when she realized what he'd said.

“Anquares and the Sight of Magic.” Celestia said, reading the title on the spine. "I can see where your confusion came from.”

“It's not entirely misplaced Princess.” The head librarian said, smiling. Tall and regal, nearly reaching Celestia's height, though with none of the princess' quiet power, the earth pony was steel gray with a dark mane. A file folder was her cutie mark, though a book peered out of it, rather than sheets of paper.

“Hello Book Binder.” Celestia said, turning towards her. "How do you mean?”

“Turn to the back section.” Celestia did so. Then she blushed. "So you see, it's not a public tome.”

“Indeed. Perhaps it should be more clearly marked.” Celestia said, passing the book to the librarian.

“I will see that it is done.” Book Binder said, taking the book. "If you'll excuse me, I've got some books to reshelve.” she headed off to direct the other librarians at their task.

“Now, let us see if we can locate the proper book.” Celestia said. She and Luna went one way, Twilight and Robert the other. Shortly, they returned to the table, each with a book they suspected would help.

“Princess?” Twilight asked her former mentor suddenly.

“Yes?” the white Alicorn asked.

“Didn't you once tell me that the nobles should never be left long to their own devices?” Twilight asked. "Doesn't you being here mean they're all standing around waiting for you?”

“It would, but before I came to my sister, I told them I would expect a budget proposal upon my return.” Twilight shuddered massively. "I suspect that will keep them occupied for some time.”

“We have looked at the records sister. In my thousand year absence, not a single time did they agree on a budget.” Luna said. "Even in years with a clear surplus.”

“I know. It is my go to plan when I must leave. They all wish to please me, so they try very hard. I am never surprised at how well they solve problems I did not know existed.” Celestia smiled. She turned the page. Luna turned a page. Twilight turned a page. Robert turned his book upside down. The others shared a look. He flipped a page, made a noise and turned it over again. They continued like that for several more minutes.

“Ah ha.” Luna said. "I believe this is it.” she slid her book into the middle of the table.

“Dill Whips Dazzling Dweomer-vision.” Twilight read. “A spell to see power in action.” she read through the spell and let Celestia have the book.

“I think perhaps this could work. Though, we need a test subject. three sets of eyes settled on Robert.” He stared back, then shrugged. He flipped a page. Three horns glowed. Eyes flashed white and then snapped closed.

“He could not have that much power.” Luna said.

“I do not understand such strength.” Celestia said.

“I don't think it's him.” Twilight said. "He's cut off from his magic. He had a magical accident, and so he has wings, but can't use his magic.”

“Sorry, I forgot about the wings. Robert said. "Wait a moment. he backed up a short distance and stretched his wings over his head. "Try now.” Eyes opened.

“Better.” they said together. "I think that this is too strong for the purpose.” Celestia clarified.

“Hold on.” Twilight's horn flashed once. Then again. “Ah, change the entropic constant to a lower number. I used 3.77.” more horns.

“Ah, much better. If you could turn the wing?” Luna asked. He did.

“Me, it's full of stars.” Celestia said. Twilight facehoofed. "Oh come on, that was funny.”

“Not really.” Luna said, chuckling. "Though I see what you mean.”

A sphere of magic floated past, followed by a gasp from Twilight. Several more spells flickered to life and died as she watched. “I have found the downside.” Twilight said.

“Which is?” Celestia asked.

“It's very difficult to write while using this spell, unless you have mastered using a hoof, and since I have not...”

“Ah.” The spells faded and Robert tucked his wings away. "Though perhaps you will find more use from it, having such a faithful assistant who does not need magic to write.” Celestia smiled. She led them out of the enclosure and returned the key to the head librarian who thanked her. Three Alicorns and a winged Tiger were a bit of an odd sight even in Canterlot itself. As they left the building, they ran into an unexpected pony. A pale blue unicorn with white mane joined several others in bowing, in an attempt to remain hidden from the eyes of those three Alicorns. She needn't have bothered, since they were talking amongst themselves, Celestia having invited Twilight to lunch with her and her sister. Luna wouldn't normally have agreed, being a night time pony, but she couldn't resist the chance to join Twilight in teasing her sister.

Robert noticed the unicorn and smiled. He broke off from the rear of the procession and trotted over to her. He'd met her on his way to Ponyville, finding her on the road to Trottingham, with only a few bits to her name, earned in card games where her sleight of hand had gone unnoticed. She'd stumbled into the tree he'd fallen asleep in, and collapsed from exhaustion. He'd not noticed her until he'd awoken and found her huddled against him for warmth. Upon awakening, she'd been terrified, and begged him not to eat her. She'd been supremely surprised to find him laughing in her face. Then he shared his breakfast, and pulled much of her story out of her. She glossed over Ponyville, the first visit saying that she ruined herself, and the latter simply that she'd done bad things she'd rather forget.

To say they were friends was a bit of an overstatement. It had been more of a business arrangement. She became a temporary Tiger tamer, and he became a 'savage wild tiger', from the tribes of the far east. It wasn't great money, but it put her on her feet, and him on the path to Ponyville.

“Trixie?” Robert asked. She jumped at the sound of her name, and then again when she realized who was speaking.

“Robert!” she threw her hooves around his neck, and he returned the hug.

“Trixie?!” Twilight was surprised to hear the name and she turned. Trixie caught sight of Twilight, and the Royal sisters approaching. From her position they seemed to be bearing down on her, and after her previous shock, she did the only sensible thing. She fainted. "You know her?” Twilight asked, indicating the now comatose unicorn.

“Yes. And it seems you do as well.” Robert replied.

Luna interjected. “Sister, perhaps we should make it a lunch for five?” Celestia nodded, very interested to meet The Notorious and Infamous Trixie.