"No, no, this simply will not do at all," Rarity muttered to herself, replacing another bolt of material on her shelves. The Doctor ignored her. He brooded over the loss of his coat, watching in moody disinterest as colors and patterns and textures swirled around him under the unicorn's critical gaze. He barely looked up as she exclaimed, "Oh! I am getting a vision…Yes, it will be positively divine! promise you, I will make you look and feel tres magnifique!"
"I feel as though I've lost a dear friend," the Doctor said flatly. He wanted to sulk, but as Rarity's magic did its work he began to grow interested in its source, in spite of himself. "Since I am obviously not going anywhere, perhaps I could have a few questions answered?"
He almost had to laugh; it sounded like something he might say to the Master or Davros or any of the other evil entities who had captured him down through the centuries. The unicorn Rarity hardly seemed like the villainous sort. She was far too… cute. It was hard not to like her, even after she had forcibly separated him from his favored fashion. Her joy in her creative process was almost infectious, much like the charm of the town had been for him earlier.
"Ask away, darling. I would never refuse help to someone seeking to better themselves. With my guidance I am certain you can learn to dress with class and elegance."
"Not quite what I had in mind," he muttered, adding aloud, "Actually, I was interested in learning more about your magic. Exactly what other things can you do with it?"
She glanced at him in surprise. "My magic? Why would you want to know about my magic? You should already know enough about magic, especially since you have magic of your own—but wait a minute! That's impossible! How could an earth pony such as yourself be capable of magic?"
The Doctor smiled. "Not magic, my dear. Telepathy. Mental disciplines honed over years of study under the auspices of my Time Lord tutors. Although... it didn't seem to mix well with your magic, did it… and the TARDIS has telepathic circuits… Tell me, are there such things as transformation spells in your world?"
"Of course, it's all so simple! Lost in translation, or rather, translation circuitry, I suspect. Poor old girl got a bit confused. Not sure why I didn't think of it before, really. I suppose I have my sense of adventure and insatiable curiosity to blame. Something unusual happens and my first inclination is to go exploring. Never entered into my mind that my own TARDIS might have contributed to the problem." He tried to shrug out of Rarity's half assembled creation as he moved towards the door but gave up halfway to his destination, allowing the ribbons of fabric to trail behind him like the tail of a kite.
Rarity stared after him.
"Wait! Where are you going? I've not even completed your new look yet! What will everypony think when they see you leave my shop looking like this?"
"Tell them I'll be providing the decorations for Pinkie's celebration," he replied impatiently, figuring he could probably do an admirable imitation of a piñata, festooned in his fluttering bits of cloth.
"I knew you'd be excited over my party!" an unexpected voice shrilled in his ear. The Doctor stumbled to a stop, stunned to come face to face with Pinkie Pie. She continued on, not noticing his shock at her abrupt appearance, "but you really didn't have to worry about that because I got a ton of balloons and streamers to match your coat and…wait just a teensy weensy little moment. Where's your coat? You have to wear your coat to my party! I themed the party after your coat!"
The Doctor glanced back at a frustrated Rarity. "Well, you will simply have to change your theme. I've disposed of the horrid thing," the unicorn declared.
Pinkie's face fell, but then she brightened up again. "Oh, that's all right, I betcha I can find it again." She giggled, turning back to face the Doctor. "Besides, you'd look pretty silly wearing that to the party. You'd clash with all my decorations!"
Rarity fidgeted as Pinkie dashed off. "She won't find it. She simply can't! All it is now is a pile of scraps…" She broke off suddenly, gasping in dread. "Noooo…" she wailed.
Pinkie Pie bounded back towards the two other ponies. Slung over her back like a patchwork saddlebag was the Doctor's coat. "Told you I could find it!" she announced with a delighted giggle.
The Doctor stared at Pinkie with a newfound awe and sincere gratitude. "Thank you, Pinkie," he said, taking his coat up in his teeth. He struggled to get it on but eventually stood tall, arrayed in all its Technicolor glory. Rarity winced and looked away. "As generous as your intentions were, Rarity, my sartorial selections must remain unchanged. You see, this coat is very important to me," he added, nosing the cat badge on his lapel into position. "A dear friend of mine greatly admired this coat and I swore that I would wear it in her honor."
"Awwwww, that's so sweet!" Pinkie gushed, jumping up and down in her excitement. "So it's like a super-duper extra special stupendiferously important coat! I knew it, I knew it, I knew it!"
Rarity risked a glance towards the eye-searing display. "I suppose...in this new light…it's not as horrible as I thought," she said, her gaze immediately shifting away again.
"And now if you will excuse me, I have to return to my TARDIS. I have the feeling many of the answers I've been seeking can be found there." The Doctor turned from the two ponies, but Pinkie's disappointed wail stopped him in his tracks.
"But you can't go yet! Everypony in town is going to be at the party and it would be so bad if everypony came except for the pony that the party is for and—"
The Doctor sighed. He wanted to find out just what part his TARDIS might have played in his transformation, but he did owe her for rescuing his coat for him. Without her it would have ended up as a bundle of rags in Rarity's shop. And, a party in honor of him was highly flattering, after all…
"I suppose I could stay for a bit longer," he conceded.
"Yay!" Pinkie shouted. "I even found the best location for it. See, there was this funny blue box-looking thingy in the woods, and I peeked inside and it was all gimungously huge inside and I spent the entire day decorating it for the party and I bet I could get everyone from Ponyville inside!"
The Doctor's eyes widened in alarm. "You threw a party in my TARDIS?!"
Maybe he could get used to being a pony if he just made his escape now?
A/n: I hope I haven't made Rarity too aggressive in this fic. I don't want it to seem as though she is attacking the Doctor, I hope it comes across as she got carried away while trying to help somepony she thought was in need. Hopefully the theory for the Sixth Doctor's transformation doesn't sound too convenient. I just had a scene in my head that tried to get away from me and reined it in as best I could. Just didn't seem right to leave Sixey without his iconic look. :) Please let me know if this works, or if it doesn't, I'd love to know why. Appreciate all who have taken a chance on this little fic and hope you enjoyed it!