"Let's see, this spell should do nicely. As much as it pains The Great and Powerful Trixie to even consider using a costume spell, it must be done for the good of the show. After all, nopony could mistake THIS beautiful form for a colt."

The G and P Trixie closed her eyes, horn glowing as she concentrated on the enchantment she had only reviewed once. A pony as skilled in magic as Trixie does not need to reread such a simple spell. Starting from her horn, which grew longer and sharper, to the broadening of the shoulders and losing the lovely curves of her flank, it seemed the spell had worked perfectly.

"Wonderful."

Trixie admired her work in the mirror. The male form was nearly as handsome as Trixie was beautiful, though nothing can dream of reaching such perfection. But something was amiss. The form was suppose to merely be an illusion, but as the seconds ticked by, she realized that her normally comfortable cloak had become quite snug around the thicker neck, and a subtle difference in how her legs felt confirmed it. She was now a He.

"By Celestia's Beard!"

And with that, The Great and Powerful Trixie fainted.

...

"The library's closed, come back in the morning!"

Twilight Sparkle rolled out of her bed, annoyed as the knock persisted. She grumbled as she made her way downstairs, and sighed as she opened the door.

"We're not op-"

Twilight was shoved aside as a male unicorn forced his way inside. Twilight looked him over, an odd sense of deja vu creeping over her. His hat and cloak seemed familiar, as did the hat. But it was the haughty way the pony carried himself that, for some reason, made her bad mood worse.

"Sir, it's Two in the morning, and I don't care how badly you need a book, we're closed!"

"You listen here, foal! You should be grateful, as I, The Great and Powerful Trixie, have come to you with a request. It seems my magnificent magical mastery surpasses even my own high standards. A simple costume illusion spell turned into a transmogrifying one and I have need of YOUR collection of arcane tomes to amend this... overshoot."

Twilight's jaw hit the floor as it all sunk in. The form before her was male, and yet she had no doubt that everything he was saying was true. Trixie must have misread something from where she tried to learn the spell, as even the biggest failure in an illusion wouldn't do this. Congratulations would have been in order, were this anypony BUT Trixie.

"Alright, this is a library, I won't tell you you can't read one book or another. But do not think for one moment that you're going to drag me into researching the counter-spell for you."

Trixie merely gave a condescending laugh.

"As if The Great and Powerful Trixie would need your help."

Twilight rolled her eyes, and began climbing back up the stairs to her room.

"Well, come back in the morning, Trixie. You let yourself out."

"I was um.. planning on staying here, to reduce the number of ponies who see me in this condition."

Twilight snapped back around, glaring at the imposing pony. She opened her mouth to object, but seeing Trixie, or rather Trixter since she could hardly think of her as Trixie in that body, act something not unlike sheepish, caused the thought to leave her. Instead she merely sighed.

"Alright Trixt- I mean Trixie. Come use the spare bed. But any funny business and you'll have to rent a room elsewhere."

Trixie recoiled from the shock of the implications.

"Are you assuming that just because this body is male, Trixie would 'try something' with a homely little filly like you? The idea is preposterous."

Twilight blushed in shame, and not solely from insulting her without reason. By implying the funny business, it meant she had thought about her, and Trixie, doing... well the thought need not continue. Perhaps helping Trixie was a good idea, to get her back to normal and more importantly, far away, sooner.

...

Two weeks had gone by, and they were no closer than they were at the beginning. They had agreed to claim to be cousins, with 'Trixter' visiting for a while. Spike was wary at first, but was too glad of having another guy around to spend much time thinking on it. Everypony else was quite friendly about it, though they did wonder how such a polite filly like twilight could be related to such a snobbish colt. Pinkie threw a party for him anyway, which he had enjoyed greatly for being the center of attention. But all this was just a reminder that Trixie was still stuck in that body. In frustration, Trixie threw a book against the wall.

"Ugh! These foals never thought to prepare to such a talent as mine! I hate this body! I belch, I get asked to do all sorts of hard physical things, and if I think of that blasted purple pain, it reacts so crudely!"

She collapsed in a huff. It hadn't been so bad at first, but after the accusation, something in the idea of being with that magical menace appealed. The calm breathing in her sleep, the movements of her lips when she focused on a difficult spell, the sway of her tail bringing out the best in her flank... Trixie flushed deeply at the thought, cursing the body for reacting in such a way. Her face wasn't the only place blood was flowing, much to her dismay. Trixie breathed deeply, trying to calm herself.

"Trixie, you alright? I heard you from upstairs!"

The blue unicorn quickly pulled the book into his lap, as a towel wrapped Twilight stepped into view. Trixie tried to avoid directly looking at her. She'd come out of the bath, and the scent of her floral soap was faint, but it stirred something in the accursed male body.

"Nothing, just uh... I fell grabbing this book from the shelf, which is why I am laying in the floor and why it is on me."

Twilight raised an eyebrow at how un-Trixie it was to admit an accident. She pulled the book away, looking the title over. She heard a protest from Trixie, but ignored it as she flipped through it.

"I know you're a show-pony but I thought you were here for magic documents, not one of the romance novels Rarity enjoys so much."

Trixie was turning a shade of purple, her reddening filtering through the blue. She gathered herself off the floor, glad Twilight's attention was elsewhere. The smell of flowers was thick as she walked closer, and despite her annoyance at the words spoken, she could not speak. She felt light headed, as if she'd enjoyed some of Berry Punch's best vintage. Before she knew it, she was right beside the preoccupied Twilight, who was reading the book with a bemused look on her face.

"This is terrible. 'The stallion's breath was warm upon her ear, but it was his words that heated her. My darling, he said, I want nothing more than to please you, my body is at your service.' Rarity has such poor taste."

Trixie was so close to Twilight's side, she could actually feel the heat of the bath still radiating from her. The transformed filly's eyes were drawn to the unicorn's neck, watching the water droplets still on the throat move with each breath. Trixie leaned in, and gave a soft puff, blowing some away but also causing Twilight to shudder. The unicorn snapped the book shut, blushing deeply. Trixie realized what she'd done and coughed sheepishly.

"I noticed you were dripping and thought... well, nothing. I wasn't thinking."

Twilight fidgeted, looking down at her hooves.

"You... you can do it again if you like. It was just a shock, I was getting a bit drawn into the story. It's surprisingly... well written."

Twilight stood still and began reading again, both of them merely standing, wondering what the other could possibly be thinking of them. Trixie leaned forward, and rather than on the neck, blow gently across her shoulder, evoking another shudder from the filly. Twilight gave a whimper as the breath went over her flank.

"Everything alright, Twilight?"

Trixie stepped in front of her, a rare look of concern creasing her face. Twilight gave a ragged sigh, an ember slowly growing into a fire. Trixie seemed as if she was about speak but words weren't what Twilight was wanting. She leaned forward, forcing their lips together. She could feel the warmth off Trixie's face, but blessedly no movement away. Twilight pressed forward once more, forcing the other unicorn against the wall as the passion commanded her tongue to invade.

The kiss was broken when Spike walked in, carrying an armful of books. The pair quickly disentangled from each other, panting to try and cool the burning inferno within. Spike just look at them quizically, and put the stack down to go get another. Twilight went down into her underground lab, while Trixter went up to the bath. Fires were burning, and though there was only one way to truly please it, the pair set about the private task of calming down. When it was done, Trixie was glad she'd chosen the tub for the deed. Rinsing out bath water, she only think how nasty it was to be a colt.

The next day,the basement door slammed open, a new unicorn walking up into the library. At first, Trixie and Spike didn't know who it was. But the shade of purple gave away the identity.

"Twilight Sparkle?"

He nodded.

"Well, I suppose I should go by Dusk Shine like this, but I figured out which spell you'd used. It's a little rough to get right the first time, I'm surprised you managed it. But it's easy enough to undo."

A short explanation later, the two fillies stood awkwardly in front of each other. Twilight was the first to break the silence.

"If you want, you can stay here longer. You do have a lot of talent, maybe with some proper training, you'd turn it into something even more impressive."

Trixie blushed slightly, and coughed before she spoke.

"No, you know how it is. Adoring fans simply can't wait for the next time The Great and Powerful Trixie comes in to town. I can't let them suffer any longer. But I'll see about coming back for a new show here in Ponyville once I do a few of the most profitable venues to give me some extra funds..."

Trixie gave a brief smile and headed to the door, before she opened it, Twilight had teleported in front of her. Trixie opened her mouth, but it shut when Twilight gave a teary eyed look.

"Alright, I have something to give you before I go anyway."

Twilight smiled softly, and was about to ask what it was, when Trixie's lips met hers. It was only for a second, and then she was surrounded in smoke. The door slammed open, and all that was left behind was the sound of running hooves, a confused unicorn, and a single frustrated tear soaked into the dust on the floor.