A/N: Disclaimer: I don't own it. Seriously. Would you really like to see this sort of stuff on TV?

So I'm sat here giggling at 'Under The Sea' from the Disney movie The Little Mermaid (We do they got? A lot of sand! We got a hot crustacean band!) - which by the way, I've never seen - and this came to me, and I couldn't seem to get it out my head. But why I wrote about cats instead of fish, I'll never know. General structure inspired by Red Dwarf's Bodyswap episode from series three, of course. Not proofread. I'm sure you'll live. :)

"Don't worry Rose, I know exactly what I'm doing."

Rose sighed dejectedly, knowing full well if she couldn't even trust the Doctor, she couldn't trust anyone.

"Okay. But I still don't like this idea of this, y'know."

"Honest, it's foolproof," the Doctor simply answered back, sitting down in the rather lethal looking contraption flowing with fatal electrical current and tying himself in the best he could.

Rose looked at him, then at the tiny tabby kitten sitting on the other chair of the machine strapped in. Then at the Doctor. Then at the kitten. Then back at the Doctor again; and gulped.

"Don't you think the RSPCA would have somethin' to say 'bout this?" Rose asked mildly as the Doctor beckoned her with his free hand to help him strap in.

"Well, what we don't tell 'em won't hurt 'em. Besides, this is a good thing for cats. This machine can, allegedly, make me allergic to cats or vice versa. I'm just being the unassigned product tester."

"If you mean by 'unassigned' as chargin' into this top secret science experimental lab on Planet of the Geeky Spotty Scientist Freaks Who Live In Their Mum's Basements and 'accidentally' blowin' up the establishment and sendin' all the scientists to the neighbouring planet then feelin' free to test their equipment in their absence – then I guess I have no objection."

"Ah, I knew you'd understand!" The Doctor beamed, testing out the metal rings clamping him to the chair to find they were offering the maximum amount of bondage. "Press the green button, would ya?"

"I seriously hope you know what ya doin'…" Rose muttered quietly, more to herself than the Doctor – and pressed the button.

There was an almighty crack of pure electronic energy, and suddenly the whole room was dancing with rebounding electrical sparks. Rose screamed and ducked to the floor with her hands over her head, but her screams only joined that of the cats and the Doctors.

Hearing the Doctor's yells of pure, undivided agony, Rose found a strength rise within her for her best friend, and bolted bravely onto her feet. She scrammed back over to the vivacious machine, heading straight for the control panel fully realising that the Doctor had gone quiet.

Glancing over the buttons, she had hoped to see some kind of big, red emergency stop button marked 'STOP', but typically there was nothing but small coloured buttons covering every inch of the panel.

She had no other choice. She had to do something.

She wagered her bets on a nice blue coloured elevated button, and took a nervous gulp of air, whacking her hand down on it.

To her utter relief, the electric bolts suddenly started to disappear into nothingness and the machine powered down to minimum again. She immediately looked over to the Doctor to check on him, but his eyes were closed.

"Doctor?" she asked, hesitantly. He didn't reply. That's when she knew she had to take charge. She knew where the TARDIS was; she just had to find a way to get the Doctor home without breaking her back whilst trying to give him a fireman's lift.

She glanced around the room for anything that could help her – ever since she'd started travelling with the Doctor she'd learnt to use everyday objects and put them together to achieve means they weren't even designed for. Like a plunger to climb a mountain…that had been a fun day…

The wooden door that the Doctor had kicked in upon arrival after the sonic screwdriver had proven useless still lay abandoned on the floor, coupled with tangles of coloured coded wires scattered randomly. Idea.

Rose felt more like a lumberjack towing a sled of wood than a nineteen-year-old girl as she dragged the door with the unconscious Doctor tied on back to the TARDIS. She was only glad he was much thinner and lighter in this body – because she already felt like her back had just cracked out of place.

Plus, she had brought the kitten too. What was she supposed to do? Just leave it there to die? It was currently tucked unconscious like the Doctor into her coat, although it was just like it was snoozing happily on a rug by the fireplace. She'd have to give it a name.

A quick check had told her it was a girl kitten, so immediately several names leapt to mind. Mrs Cookie. Snoocums. Dixie. Fufu. Flossie, she decided. It looked like a Flossie.

She made it to the TARDIS, and had to open both the doors to get the Doctor inside. Once inside the control room however, she finally gave up and collapsed into the captain's chair, pulling the Doctor's trenchcoat over her and closing her eyes, breathing like she'd just completed a Triathlon through a peat bog.

She knew she must have fallen asleep at some point during this, as the next thing she heard was some desperate, painful sounding 'meowing' coming from somewhere over the other side of the console room. She immediately panicked at the sound of Flossie in pain, jumping onto her feet to help the poor thing, before realising, with slight shock, that Flossie was still curled up inside her coat.

Then where was that meowing coming from?

She looked over at the Doctor still bound to the door, and her jaw dropped.

"Meow!!!" he whined in that heartbreaking squeak, thrashing round under the wires that held him to the wood so tightly.

"…Doctor?" Rose asked, bemused.

"Meeeeow!!!!" he cried again, looking straight at her with wide, pleading eyes.

"Okay, okay, I'll untie you!" Rose laughed, slipping a sharpened penknife out of her pocket and kneeling down next to him to cut him free. As she lowered the blade to the wires next to the Doctor's arm, he meowed in alarm, squirmed and hissing, spitting like, well, like a cat.

"Doctor please! Don't be difficult!" she said in alarm, narrowly missing her finger with the penknife as it went out of control. She quickly hacked through the wires until he was free, and he bounded into four feet and sped off down the ramp, jumping into the recess between the grating and the walls of the console room.

She was about to go after him, but suddenly felt something moving inside her coat. Flossie had woken up.

Forgetting the Doctor for a moment, she slipped the kitten out of her coat and cradled her in her arms, watching Flossie stir and open her cat eyes.

"Meow," she said quietly, and then went rigid in Rose's hands. "Meow? Meow?!" She looked back and forth between herself and Rose in alarm, before suddenly pummelling at Rose's chest.

"Oh don't tell me both of ya have gone weird?" Rose asked with a sigh, tickling Flossie's chin cheekily.

"Meow!" Flossie simply replied, jumping out of her arms and smashing, rather painfully, on her back in the middle of the floor.

"I thought you cats could land on all fours?" Rose asked, quite aware she was talking to herself - first sign of madness. She got onto her knees beside the kitten, lifting her caringly onto her four feet.

"Meow!" Flossie said, bolting over to the Doctor's coat still laying abandoned on the captain's chair from where he'd left it that morning, and jumped up to grab a hanging piece of it's material between her teeth. Rose immediately stepped forward toward her, raising a forbidding hand.

"No, don't touch that Flossie…" she started to say to protect part of the Doctor as the coat hit the floor, but suddenly stopped.

"Meow," Flossie cooed in a soft whine, first pointing at herself with a paw, then at the coat.

"…Doctor?" Rose whispered disbelievingly, "but…you can't be."

It was then the Doctor reappeared, or at least, his physical form. He walked on all fours towards Rose, rubbing up against her leg fondly, purring loudly.

Rose looked back at the physical appearance of Flossie.

"Okay, you've convinced me."

It was all well and good that Flossie was infact the Doctor, and the Doctor was Flossie – but Rose really did not have the foggiest as to how to reverse the process.

Even if by some miracle she managed to get the both of them to that machine without Flossie (Understand, when she was now thinking of 'Flossie', she was now thinking of Flossie in the Doctor's body, and when she thought of 'the Doctor' she was actually thinking of the Doctor in Flossie's body…) running off to explore, how would she operate the controls? She might end up destroying both their brains at the same time.

Besides that, maybe Flossie might inadvertedly hurt the Doctor's body if she wasn't careful. She didn't really want the cat to waste a bunch of his regenerations in less than two minutes.

So, she decided with her own authority, that she would sort it all out in the morning.

She explained this to the Doctor, who just meowed in reply, following her back to her bedroom. He was a very modest cat, and still looked away whilst she got changed into her night things. It was probably a little out of order, but she couldn't help thinking he was an adorable wittle kitty cat, and did she really want to change him back?

She quickly dismissed these thoughts as she slipped into bed and brought the cover up over herself. She was just switching off the light when she felt a delicate pressure on the right side of her double bed, and suddenly the Doctor appeared next to her head, his two cat eyes glowing in the dark.

He curled up next to her and she smiled to herself, stroking him over the head before bringing her arm to her chest and turning over slightly onto her side, closing her eyes.

"Meow!" came another voice from outside her already open bedroom door, before Flossie appeared in the crack of light from the low level glow outside.

She bounded onto the bed with a huge bounce, nearly sending the Doctor flying off of the bed and onto the floor. He hissed at Flossie, turning up his nose and walking back over to Rose to reclaim his previous position.

Flossie crawled over to Rose and purred loudly, all seeming so bizarre and unheard of coming from the Doctor's body. She rested her head on Rose's stomach, and she stroked Flossie's head too. She'd never thought she'd see the day where she could say she'd slept with two cats, both part of the man she loved.

Finally content, Rose closed her eyes to sleep – but not before the Doctor had reached up and gently licked her face affectionately.

She had spent all morning trying to figure out what to do to get the Doctor back in his own body. The Doctor obviously knew the answer, but he couldn't communicate it with her – so they'd spent a majority of the morning trying to figure out a system where they could communicate.

So now they were in the library, and the Doctor was attempting again to speak to her. He was 'meowing' a lot; jumping up at down infront of a shelf of books at a particular one he wanted her to take down.

"This one?" she asked, pointing to a red backed book on 'Gallifreyan Geometry'.

The Doctor shook his head, continuing to down up and down.

"This?" She pointed at an oversized book the thickness of the Harry Potter series put together, this time labelled 'The Merry Adventures of Katie Throppet'. He inclined in a negative again, and Rose pointed at the next book, reading off the title, "'Instructions On How To Operate Your Windmill'? Are you sure 'bout that, Doctor?"

"Meow!" he chimed, running forward towards her as she pulled out the extremely old book, the dust puffing up into a thick cloud as she dropped it onto the floor. She sneezed loudly, holding her arm to her nose to protect herself.

The Doctor pointed at the manual. He got onto his two cat hind legs and held two paws above his head, miming bringing them down onto his head. As the imaginary hat hit his head, he started jerking around to imply an electric shock, and then fell back on the floor and stuck his legs out at different angles, his cat tongue hanging out his mouth. If the situation wasn't so serious Rose would have been laughing.

"There's a instruction manual…" she started, trying to figure out his actions. "There an instruction manual to the machine…?"

"Meow!" he danced around in the affirmative on springy legs.

"There's an instruction manual to the machine, which I need to find!" Rose finished, amazed with her own intelligence. Then her face fell. "Er…where is the manual?"

The Doctor raced out the door at super cat speed.

Rose had opted to leave Flossie in the TARDIS whilst she and the Doctor went to find the manual – she'd only run away otherwise, and Rose knew the TARDIS would look after her whilst they were gone.

They were sifting through a ton of documents on various science experiments, but couldn't find anything on the strange machine on Deck A. It was by sheer luck Rose managed to pick up the right piece of single paper in the entire box, and it was translated, too.

"Got it!" she yelled in delight, waving it about infront of the Doctor.

"1. Press green button.

2. Wait.

3. Press blue button to stop.

Note: Works either way."

Rose stared at it.

"Oh my God!" she shouted, slightly angry with herself for being so dumb. "This whole thing could've been sorted out yesterday if I'd have taken the risk!"

But the Doctor had already leapt up in the machine, eager to get on with the process. Rose dropped the instruction sheet and walked over to him, strapping him into the contraption securely.

The Doctor waited whilst Rose went to get Flossie, sitting down contently and practising purring, swishing his tail playfully. Then he got this feeling. Something was…something was in his throat…

He started to retch, trying to bring up whatever was stuck in his throat. It was slowly starting to come up, up and up his throat. It felt horrible. It was like being sick in slow motion.

He felt something pop into his mouth, and the feeling was gone. With insurmountable disgust, he spat out the offending object onto the floor below, peering at what it was.

It was a hairball.

Oh, how he longed to have his body back.

Rose arrived back with Flossie, leading her by her jacket collar over to the machine. Flossie began to lick her jacket, purring as she strapped her in. Rose ruffled her hair and could only grin at the Doctor, who had narrowed his eyes ever so slightly.


Rose pressed the button.

The Doctor felt ill.

He groaned loudly, turning over and holding his aching stomach, wanting to throw up. He opened his eyes and found he was lying in his own bed, Rose sitting next to him, smiling broadly.

"Is that you, Doctor?" she asked tentively, tapping her fingers over his chest to stop herself from hugging him tight before he knew he was himself again.

"I hope so…" he said weakly, pulling up to sitting position.

"Yes, you're back!" she grinned, jumping onto him and throwing her arms around his neck tightly. "How ya feelin'?"

He ran a hand over his coccyx, just to check there wasn't a tail waving majestically there. No. Nothing. He slipped out his tongue and tried to touch the tip of his nose – but that wasn't possible either. Rose backed off of him as he lifted the covers of his bed up gently and looked where it mattered; and to his immense relief he found he still had everything down there.

"I feel sick," he groaned, holding his stomach. "Get me a bucket…"

"Thought this might happen…" Rose grinned, pulling up an already present orange bucket from somewhere at her feet and handing it to him. He stuck his head into it and violent vomiting sounds ensued. Rose could only wince.

When he finally finished, he brought his head out again and collapsed again the covers.

"What has that cat been eating?"

"Rats, mostly."

The Doctor's face turned pale again in an instant, and threw his head back into the bucket. Thirty seconds and he finished, setting the bucket down on the other side of the bed from Rose and turning back towards her.

"So, how was life as a cat?"

"Well…" the Doctor mused. "I coughed up a hairball, kept wanting to lick parts of me I never even knew existed; I continuously wanted naps, everything was ten times too big, you kept calling me Flossie and I was also a girl cat, who kept having erotic thoughts about this cuddlytoy male cat I found in the junk room. But apart from that - yeah, it was great. Where is that furball anyway?"

"Still sleeping, I think."

Flossie suddenly jumped up onto the bed at the Doctor's feet, and strolled casually up to him. She proceeded to lick him up his cheek lovingly, but the Doctor reeled, obviously seeing it differently.

"Get off! I know where that tongues been!"

The End