Author's Notes:
This was written for Remix Redux, as a remix of "Unreasonable" by pedanther, which, according to the author's notes, was itself written as a challenge involving writing a five-sentence fic with a completely unreasonable first line. I find this quite amusing for some reason.

Note: This involves some stuff about food, exercise, and physical fitness (or the lack thereof), which I know can be a particularly sensitive topic for some. There's nothing very serious in it, though, and (I most certainly hope!) nothing that should be offensive to anyone.

"I can guarantee it, Mel," the Doctor said as the Time Rotor stilled and the TARDIS wheezed its way to a stop. "The Alharandian Empire is the very epitome of civilization! And the food?" He actually kissed his fingers, a gesture Mel couldn't help but laugh at. "Exquisite."

He seemed terribly enthusiastic about it all. Which didn't necessarily mean very much. In Mel's experience, he could be enthusiastic about some very strange, not to mention very dangerous things. But, still. She always did like to encourage enthusiasm. "It sounds lovely, Doctor."

"It is, Mel, it is! And we should be arriving at the very height of the Alharandian culture. I promise you," he said, hitting the door control and striding confidently towards the exit. "You will be impressed."

With that, he stepped out of the TARDIS, flung his arms wide... and stopped cold. "Oh dear," he said.

Mel sidled past him and looked around. It was impressive, she supposed, in a way. They'd arrived inside some huge building. Maybe a temple of some sort? It seemed to be composed of huge blocks of brown and gray stone, with occasional touches of marble. The ceilings were dizzyingly high, the walls carved with ornate, abstract swirls. Here and there were tables, and daises, and benches that looked a little like church pews, all made of different kinds of stone.

All of it was echoingly empty, and covered with a fine layer of dust. Across the vast interior, she could see a recessed window, and through it, a long, straight street lined with buildings. They must have been beautiful once, in a slightly over-the-top sort of way, all massive stone spires and heavy arches. But half of them had crumbled into ruin, and all of them were covered in the same drifting dust.

"I think perhaps," said the Doctor, looking embarrassed and more than a little disappointed, "we've arrived just an eensy bit late."

"That's OK, Doctor." Hmm, maybe that had come out just a little too cheerful, but she did hate to see that look on his face. "I wasn't really hungry, anyway. And archaeology is interesting, don't you think?"

He only made a grumpy noise, and said nothing else. Well, best to let him sulk, then. He'd get over it soon enough. He usually did.

Mel moved off to examine more of whatever this place was, and immediately found herself drawn to a console of some kind. It seemed to be made of stone, like everything else, but there were delicate screens and tiny lights and switches set incongruously into its sloping top. As she moved closer to it, it lit up faintly. She could see something flickering into life on one of the screens. Symbols? Writing? She leaned closer. It was hard to make out through the dust. Maybe if she--

"Don't touch that!" The Doctor's voice boomed in her ears just as she reached down to wipe away the dust. Instinctively, she jerked her hand back, but something was already happening something terribly, terribly strange.

She couldn't feel her hand anymore. She couldn't see. But she could feel... She didn't know what she could feel. It was as if her consciousness was being stretched and kneaded like dough, twisted up into some new shape and stuffed into... into...

Light and sensation came back, but it all felt wrong somehow. She wasn't standing where she had been. She was closer to the TARDIS again. But the angle she was looking at the room from seemed wrong, and something about her body felt wrong, and someone was standing in front of her, by the console she'd just touched, some woman who was wearing her clothes, who was...

Who was her. Her hair, her face, her everything.

But if that was her, then who was she?

"D--- Doctor?" The voice that emerged from her throat -- the throat she was talking with -- was familiar, but it wasn't hers.

"Yes," said the person in front of her. "I am, unfortunately..." She -- he? -- looked down at herself in distaste. "...here."

Mel looked down, too. She was clothed in ridiculously bright colors, and the body inside them was most definitely not her own. "Doctor, I'm you!" The Doctor's voice, emerging from inside her, had a strange squeak she'd never heard in it before, and when she looked up she could see a pained wince on her own face. Did she really look like that? It was different from looking into a mirror. Was it because it wasn't reversed, or because she never made that expression at mirrors?

"That machine," she said. It switched us somehow."

"Yes, Mel. A truly brilliant deduction."

His sarcastic tone sounded so different in her own voice that she had to giggle. He glared at her from under his -- her? -- curls. "Sorry," she said. "Can you fix it?"

"Let me see..." His fingers -- her fingers? oh, this was entirely too confusing -- flew over the console's controls. Lights flashed. Something beeped, but not in a way that sounded encouraging. He frowned.

Oh, god. They weren't going to be stuck like this, were they?

She moved forward to peer over his shoulder, but as she did so, it suddenly went dark. "That doesn't seem good."

"Well, Mel, I have good news and bad news."

"Oh dear. Give me the bad news first." She steeled herself, and straightened. It felt weird.

"The bad news is, I can't reverse this. The machine has shut itself down, probably for good."

"And the good news?"

"The good news is, I don't have to. The effect is programmed to reverse itself automatically."

"Oh, that is good news!" She relaxed again. This also felt weird.

"The other bad news, however, is that I don't know how long it's going to take."

Mel found she suddenly didn't know what to do with her -- with the Doctor's -- with her hands. She plunged them into the pockets of his coat, but immediately pulled them out again when a dozen random hard objects seemed to be pressing into each one. "Can you take a wild guess?"

"I don't know, Mel. Hours? Days? Weeks, perhaps."

"Oh. Well, that's not so bad. Right?"

Her own face glared at her. Again.

"I mean," she ventured hopefully, "It could be worse. At least we won't be stuck like this for years." He still didn't say anything, so she continued. "What's the point of this machine, anyway? I mean, why would they want to switch bodies?"

"Oh," he said, "it was probably meant to be some sort of exercise in empathy. The Alharandians were very keen on that sort of thing. Completely wasted on me, of course. I am veritably brimming with empathy! But perhaps you will learn something, Mel."

"Yes," she said. "Of course you are." The Doctor really did have a good voice for sarcasm. Pity it seemed to be lost on him.

"Well," she said after a moment's pause. "What shall we do while we're waiting?"

"Back into the TARDIS, I think," he said. "After all, I can't have anyone seeing me like this!"

Mel tried out his best harrumphing noise, and was rather pleased with the results. But she followed him into the TARDIS.

**

The door closed behind her, and immediately the Doctor set about sending them off into the Time Vortex. He was hitting the controls with more force than should have been remotely necessary, and Mel winced as a fist thudded against the console. "Doctor, you could be a little more careful. Those aren't your hands you know. I'd rather not get them back covered in bruises."

"Oh. Um, yes. Sorry about that." He actually sounded slightly abashed. All right. One point for empathy, anyway.

He stepped away from the console and stretched out the relevant hands in front of her. "No damage, though," he said. "Look."

She took her old hands in her new hands and looked at them. There were, in fact, no bruises, but she barely noticed. She was too busy trying to process the sight in front of her. The perspective was all wrong, the hands were all wrong, the---

"Mel? Are you all right?"

She let go of him and drew in a deep breath. "Yes. I'm all right. I think. I just... Doctor, how are you not.... I don't know... Not freaking out?"

He let out an arrogant little laugh, and it sounded so very him, even in her voice, that she couldn't help but smile. "I," he said, "am a Time Lord. Change is in our very nature!" He thrust his chest out, a gesture that looked very different with her body than it did with his, and she opened her mouth to ask him to please not do that, but he kept on going. "I assure you, I can adapt to any circumstances. Even..." He looked down. "Even this. Although I must say, these clothes are even less attractive when I'm wearing them."

"You're one to talk," Mel muttered.

"And the hair..." He reached up and grabbed a fistful of curls. "Well, that's going to take some getting used to, I admit. I never had any desire to be ginger! Still." He smiled. "Might as well make the best of it."

And with that, he turned around and headed towards the interior door.

"Wait, where are you going?"

"Food, my dear," he said, not looking back. "I never did get that meal I'd planned on, and I am still hungry."

"Oh." Mel considered that for a moment. "Hang on. I wasn't hungry. And you've got my stomach!" But he either didn't hear her or was pretending not to.

She hurried down the corridor after him.

**

By the time she reached the TARDIS kitchen, he'd already finished punching his order into the food machine, and it was obediently spitting out...

She stared. "Is that a cheeseburger?"

"Yes, I'm afraid so." He looked at the plate of food with a disturbingly fond expression. "I really have spent entirely too much time on Earth. I've acquired humanity's terrible taste in food. But how could I resist?"

He lifted the cheeseburger and took a huge bite. He seemed to have trouble swallowing it. Maybe his usual mouth was bigger than hers? But after a moment he managed it, and sighed in satisfaction. Juice trickled down his chin.

"Doctor!" Mel snatched the burger away from him before he could bite into it again, plopped it onto the plate, and set it down on the table, out of his reach. "Just what do you think you're doing? I've put a lot of work into that body! I keep it healthy! I do not feed it cheeseburgers!"

"But Mel..." He reached towards the plate, and seemed unhappy to realize his arms weren't quite long enough to retrieve it without pushing his way past her.

"I mean it, Doctor. I'm not having you undo all my hard work. Why not have a nice salad instead?"

"But Mel..."

"No buts. Here." She turned back towards the food machine and dialed in a familiar program. "You have my taste buds, right? So you'll like this!"

She handed him the salad that emerged from the machine. He looked at it and pouted. Actually pouted. With her face. But he sat down and began to pick at it, with a heavy, martyred sigh.

She folded her arms -- which also felt weird -- and watched him in silence until he'd finished it.

"There," he said at last. "I hope you're happy."

"I am, thank you."

Leaving his plate on the table -- really, he could be quite the slob sometimes -- he stood up and walked towards the door.

"Where are you going?"

"I am going to the console room," he said. "To attempt to discern why we arrived in the wrong time period. I do believe the TARDIS has some explaining to do."

"When do we ever not arrive in the wrong time period?" she said. But he was already gone, and she was alone.

With the cheeseburger.

It was a very nice looking cheeseburger.

Mel's borrowed stomach rumbled.

Well, she told herself, it's not like she'd be doing anything to his body he wasn't already doing. And how long had it been since she'd eaten something that unhealthy? Maybe this was a nice excuse to indulge. Maybe just this once...

She'd eaten half of it when the Doctor came back in.

"Aha!" he cried, pointing an accusing finger at her. "I knew it!"

She swallowed guiltily. "So," she said, as brightly as she could manage. "Did you figure out what was going on with the TARDIS?"

But he refused to be deflected. "So I'm required to respect your body, but you aren't required to respect mine?"

"Now, wait a minute, I wasn't doing anything you weren't about to do yourself!"

"No? No? But, Mel." His borrowed voice had become sweetly sarcastic. "I thought you were meant to be better than that! I thought you cared about my health." The sweetness suddenly disappeared, and now he was just kind of loud. "All that carrot juice! All those exercise sessions! The rawest hypocrisy. Give you access to my body, and we see just how much you care about it, oh yes!"

He was trying to manipulate her with guilt. She knew perfectly well that he was. The problem was, it was working. And he wasn't actually wrong.

"I'm sorry, Doctor. You're right. Of course you're right." She dropped the remains of the cheeseburger into the recycling unit. "There. Won't happen again."

He looked disappointed as he watched the burger disappear.

"Oh, I see. You were coming back to finish it off for yourself, weren't you?"

"That is beside the point."

"I think it's exactly the point, Doctor. We should be looking after each other, shouldn't we? Maybe that's what the machine was intended for." She reached down and patted her borrowed stomach. "While I'm in here, I'll do my best to try to get you into shape! Just... try not to get me too much out of shape. All right?"

He sighed. "I'll try."

"Great!" She gave him a big grin. He looked at her oddly. Maybe her grin on his face looked a little strange. Well, never mind. "I'll go get the exercycle."

**

This... was not as easy as she'd expected. Why was she huffing and puffing so much? She only done a few miles so far. She'd barely even got started!

"I don't understand," she managed, between breaths. "You spend so much time running. Why is this so difficult?"

The Doctor didn't move from his position lounging against the wall. "Running is natural. Running comes easily. This..." He waved in the direction of her and the exercise bike. "...this is entirely artificial. And pointless."

"I..." Huff, puff. "...disagree."

He shrugged. "Suit yourself."

He watched her struggling in silence for a while. Then, after a particularly loud series of huff and puffs, he gave her a look that was... Wait, was that a smirk? Was he using her own face to smirk at her? "You see? Not so easy as you think, is it?"

"Well, if you'd..." Huff, puff. "if you'd just do it a little more often..."

"Nonsense. It's just the way my body is built. You humans can't help your genetics. Why should I be expected to?" He sounded strangely defensive about this. Mel wondered why, but was a little too busy trying to keep oxygen flowing and legs pumping to pursue it.

"Once I get you into shape," she huffed. "You'll see how much better it feels. You'll regret not doing this yourself!"

He wrinkled his nose. Or hers. "Just be sure to give me a shower when you're done."

She was not going to think too hard about that. Mel concentrated on pedaling faster.

**

Day four of her new Time Lord exercise regimen, and it wasn't getting any easier. In fact, she found herself often making up excuses to put it off. She'd never done that before. But it just didn't feel good in this body, not like it did in her own. Still. It was good for him. Even if it didn't help him trim down any, it must be good for his hearts. And he was doing very well with the salads, so she owed him. Didn't she?

With a sigh, Mel finished her water and climbed back on the cycle. Just a little longer. Another few minutes, maybe, and then she'd take a rest.

Muscles protesting, she began to pedal. And pedal. And pedal. And...

For a moment, she thought she'd pushed the Doctor's body too far, that she'd given it some kind of heart attack. Hearts attack? Surely the strange, twisty, disoriented feeling she was experiencing must be something terribly, terribly wrong, it must be...

Hang on. She recognized this feeling!

And no sooner did she realize that, than it was suddenly over, and she was staring down at a half-eaten plate of salad. She blinked. She raised a hand to her face. Was that her face? She grabbed a fistful of her hair. Curls. Longer ones than she'd got used to over the last few days. And her hands...

Mel let out a little shout of joy. Her hands were her hands! The Doctor was right. It had worn off. She had been starting to wonder.

Mel leapt to her feet, and almost fell over in the process. Her legs were shorter than they'd been a moment ago. And they weren't sore. How lovely!

Which reminded her. "Doctor!"

She burst out of the kitchen and ran for the console room-turned-gym, her legs feeling more familiar to her with every wonderful step.

When she arrived, there he was, right where she'd left... him? Well, right where she'd left his body, anyway. He was slumped over the handlbars, looking sweaty and cross.

"Doctor! You're you again! And I'm me!"

"Yes," he said. "And I'm all... sweaty." He made a face at her. Gosh, it was good to see that face from the outside again.

"Oh, don't be grumpy. You know it was for your own good."

He made a scoffing noise. "Well," he said, leaning back and grimacing a little. "It certainly does feel as if you were working hard."

"Thank you?" she suggested, with a little smile.

"Yes, all right, thank you, I suppose." He was the only person she'd ever met who could sound both begrudging and sincere at the same time.

"You're welcome."

He tilted his head at her and gave her a sly little smile of his own. "Not all that easy, though, was it? Hmm?"

"Not nearly as easy as I'd assumed, no. I probably shouldn't have been quite so hard on you before. I mean, I still think you need to exercise, but I can see why you didn't want to. Maybe we can start off with something a little easier, now that you're you again."

He dismounted the cycle, wincing. "Perhaps after a short rest period." She wasn't at all sure from the tone of his voice whether he meant it or not.

"Of course. In the meantime, you can have a cheeseburger now, if you like. I promise I won't judge."

The Doctor grabbed a towel and wrapped it around his neck. "Yes, well." He looked slightly embarrassed. "Do you know, Mel, I think I've developed something of a taste for salads."

Mel gave him a big grin and reached out to wrap him in a hug.

He held out a hand to stop her. "Ugh. Sweat, Mel. Sweat!"

She laughed. "Oh, why should I care about that? After all, it was my sweat a minute ago."

Unable to argue with that, he gave in and let her hug him.

"Come on, then," she said. "Come and finish your salad!"

And, rather to her surprise, he did.