As if on cue Spike returned with the books Twilight had expected, and a puzzled expression on his face she hadn’t.

“Is something wrong Spike?” she asked.

“I’m not sure…” Spike responded. “…You know that book on when Celestia ruled alone, the one with her picture on the cover?”

“Yes,” Twilight answered.

“…Well, I saw that the picture on the cover had changed so I thumbed through it, and all of the pictures show ponies as they look now.”

“What!?” Twilight gasped “Well… bring it here.”

Spike looked threw one of the stacks of books he had just brought in, having already anticipated this directive. Twilight accepted the book as he handed it to her and sure enough on the cover stood Princess Celestia, wings outstretched, mane and tail billowing in balancing directions as always, but now her body held an hourglass figure and her head an inverted teardrop shape. Twilight looked through the rest of the book and sure enough every pony, gryphon, yak, and dragon depicted in its pages stood on its hind legs, greeted with a wave of its hands or a handshake, and carried objects with hands. Twilight knew this had to be some kind of clue, but before she could complement her assistant for bringing it to her; he derailed her train of thought.

“Wow, Celestia’s as pretty as you are, Twilight.”

“S-Spike, this is no time for flattery.” Twilight protested, her lavender cheeks as red as roses. “Besides, Princess Celestia is the God-Empress of Pony Kind! There’s no way in Equesria that I’m anywhere near as pretty as her.”

“I beg to differ,” Spike insisted, “go look in the mirror and tell me that your proportions are any less than hers.”

A simple enough experiment, there was a full-length mirror on the wall to the left of the windows that stretched behind her bed. Getting up from her desk, book in hand; the student would compare herself to her teacher. Twilight held the book open to the best picture she could find, drinking in the reference so she’d know how she measured up without looking back. Finally she turned to the mirror and her eyes slowly went wide as she realized that Spike was right.

Letting her magic take the book Twilight turned and posed in the mirror to check every angel to make sure there was no mistake. There wasn’t, she was a little shorter, but accept for a pair of wings and possibly her mane, Twilight could pass as a Celestia’s daughter.

“See,” Spike said, stepping up behind Twilight to rest his hands on her shoulders, “Just as beautiful as an Alicorn.”

Twilight blushed; her heart began to race at the unexpected intimacy of Spike’s touch, and the feeling of his muscles on her back. A passage from the one book she had found that actually talked about dragons referred to them as Alpha Predators. Spike’s new form lived up to that image. His strong arms, broad muscular chest, and legs that matched his arms, certainly made Twilight think Spike could be capable of a lot of physical feats. But Spike’s touch was still gentle, like he was controlling his strength for her sake.

“T-thank you,” Twilight stuttered, lingering in the unplanned embrace “You know Spike, I think this is a clue. Or a couple of clues actually, everything looks as though this world has always been this way, also I look like a goddess and you…” Twilight lightly bit her lip and looked down. “I… I think we changed more than others because we were at the epicenter of the spell. If that’s true we may have an idea of what Harry Clopper was trying to do.”

“And what’s that” Spike asked.

“I think he was trying to become Celestia’s equal.” Twilight responded.

“Why? And how is this getting him closer to that?”

“I don’t know spike, maybe something’s wrong with the spell? Or he thought these forms would help somehow? Or maybe this is what gods look like and we’re closer to being like them now? I honestly don’t know, but either way it’s a clue.”

“Okay, so where do we go from here? How do we follow this lead?”

“I’m not sure Spike. Harry Clopper wasn’t as famous as Star Swirl the Bearded or Mage mare Meadowbrook, there aren’t any books on his life or accomplishments.”

“Do we at least know when he was working on this?”

“I think it was about 47 years ago. I think that could give us an era to reference.”

Without being asked Spike sprang to his feet and searched the history section for anything 47 years old or at least covering that era. As he gathered the best prospects he came across a book that he didn’t recognize; it had a simple hard brown cover with a lightning bolt crossing a pair of glasses on it. Spike opened it up and found it was quill written with nearly the same style as the spell book. “Twilight!” he shouted as he ran to her.

“Did you find something spike?”

“Boy did I.” he replied as he handed twilight the book. “Take a look and tell me that isn’t the same penmanship as the spell book.”

Twilight opened the book and recognized the text almost instantly; it was Harry Clopper’s penmanship! Thumbing through its pages she realized that the book was his personal journal.

“This is a huge breakthrough Spike!” She said with a smile. “Where did you find this?”

“It fell off a shelf in the history section.” Spike answered. “I must have passed over it a dozen times before but never noticed it.”

“Wait, what? That would mean that he was a librarian here after he ended his studies with the Princess.”

“Stranger coincidences have happened. Who knows, that may have been how Celestia was able to set you up with the job.”

“Maybe, but let’s figure that out later. Right now we’re looking for anything that could help us solve the mystery of what his biggest spell was supposed to be and how to reverse it.”

Twilight opened it and began reading…

3rd of Early-Fall 1960: today I begin my studies with Princess Celestia. I’ll admit I’m about as nervous as I am excited. I’ve admired the princess form a far for years, as most of her subjects would, but now to be in direct contact with her, to be chosen to study magic directly under her… I can feel my heart beating faster.

“Not too much here,” Twilight observed “he was excited to become one of Princess Celestia’s students. But who wouldn’t be excited to learn magic from the god-empress of pony kind.”

12th of early-spring 1963: We submitted our research projects today I got a B+, better than I feared but worse than I hoped. I wonder if Celestia is being deliberately merciful with me… No, any good teacher wouldn’t play favorites or let a student squeak buy with a substandard effort. I’ll just try harder next time.

8th of winter's End 1965: I have come across Star Swirl the bearded’s research on alternate dimensions, it mentions a mirror used to peer into alternate worlds, I wonder if such a construct could be here in the castle?

“A trans-dimensional mirror?” twilight pondered out loud. “I’ll have to ask Celestia about that some time.”

28th early-spring 1965: The more I study these strange bipedal creatures the more they fascinate me, the way they move, their habits and gestures, and the fact that there is a corresponding one of them for each of us.

“So that’s it,” Twilight declared “these forms are a recreation of the dominant race from one of the parallel worlds Harry Clopper saw threw Star Swirl’s mirror.”

“But that still doesn’t explain why you look like the Princess’s equal.” Spike interjected.

“Why we look this good.” Twilight Corrected. “You remember how the Mares in town reacted to the new you. You're as much a part of this as I am.”

July 5th 1965: I saw the other world’s equivalent to Princess Celestia today, she was younger than I had expected her to be, but there can be no mistake. Her majestic hair, her beautiful eyes, the fact that the others all flocked to her, there could be only one equivalent in our world. My teacher, my beautiful, radiant teacher, if only…

“If only what?” Twilight wondered out loud.

Aug. 3rd 1965: I think I’ve cracked it, a spell to not only make us the equals of these “humans” I’ve watched threw the mirror but bring me up to Celestia’s level. My radiant one, my lovely goddess of a teacher, I don’t dare right what I truly think of you, or the fantasies that run through my head when I’m not studying. But if I’m successful I won’t have to say them, I’ll be able to act on them.

“No bucking way!” Twilight burst out in surprise. “H-he had a crush on Celestia and was trying to remake Equestria so he could be with her.”

“That’s a little extreme.” Spike observed. “Look there’s one more entrée.”

Aug. 7th 1965: It should have worked. I know the spell was cast, I could feel the magic and yet the world seems unchanged. I can’t bear being this close to the Princess and yet be unable to be with her; I’ll go back to home Ponyvill and work in the Library until I can check the mirror one last time. Maybe there’s a way to check to see if I created some kind of splinter world by mistake.

“Wait, he didn’t see it work? The changes were instant when I cast it.” Twilight said utterly confused.

“Hold on Twilight” Spike interjected, “He mentioned creating a splinter world, could using the spell have created a separate world where we were always like this?”

“I… I don’t know spike.” Twilight said starting to feel her head getting heavy. “…Say, what time is it?”

Spike took a look at a conveniently located clock. “Wow, it’s half past midnight!” He observed. “We should probably get some sleep and take another crack at it in the morning with fresh minds and full sumacs.”

“I suppose you’re right,” Twilight yawned, “I’m no use if I’m too frazzled to think strait.”

Author's Note

So... I wasn't quite sure how to broach the answer to the riddle of "What the heck was that spell" so I gave some clues in the form of some observations and a few journal entrées.

It occurred to me as I submitted this that I'm the only sentient creature to have read this, so if anyone of you could be bothered to check this for errors I'd be grateful. Just... please be kind.