1. I wrote this for Round 2 of Trope Bingo. I'm going for the simultaneous double-line, and this fic fulfills my 'genderswap' and 'curtainfic' squares.
2. The pronouns were a dicey proposition; I chose to use he/him to refer to the Doctor in Rose's body, and she/her for Rose in the Doctor's body, seeing as both of them still identify as their original genders despite this new situation. Hope that helps prevent some confusion.
3. This is also posted at AO3.

"What do you mean TWO WEEKS?" the Doctor shouted into his mobile at the hapless Torchwood lab technician on the other end. "Of all the bloody—"

"Doctor," Rose admonished him.

"Look, I'm sorry Kev; but I'm sure you understand—under the circumstances—my concerns," after another moment, he said, "Ta," and ended the call. To Rose, he said, "Two weeks. Two weeks we're stuck like this," he gestured between them.

Rose looked at the Doctor, standing there limbs akimbo on curvaceous hips. "Two weeks isn't a big deal, Doctor; we'll get through it." She stuffed her hands into her pinstriped trousers.

"They won't even let us come into the office for desk duty," he protested, reaching to the ruffle short brown hair at the back of his head and finding long blonde hair instead. He jerked his hand back, the gesture providing none of the comfort it usually did; instead he went for his ear, and when he gave it a pull, he was disappointed by the different feel of it, and the small gold hoop that impeded his grasp, and thus his ability to ignore the glaring problem here. He looked down at himself. Make that two glaring problems.

Rose giggled as the Doctor noticed his breasts—well, her breasts. His breasts. Oh, this was going to be a confusing two weeks. His expression began with disbelief, then contempt, then embarrassment, paused at mischievous interest and finally settled on irritation. "Who the bloody hell even invents a body-swapping gun?!" the Doctor whinged, but it came out sounding so much like a patented Jackie Tyler shriek that the Doctor nearly jumped, clapping a hand over his mouth.

Rose smirked and replied, "Maybe certain people trying to get around the illegalization of the psychograft." She walked toward him awkwardly, still not used to the higher center of gravity in this body, or the way she has to walk to accommodate the extra…parts she's not used to. "At least neither one of us is in physical danger," she said, taking the Doctor's hand. Her mind reeled a little bit at the knowledge that it was him, but the hand wasn't his and it wasn't unfamiliar either.

He bit his lip, and Rose smiled a bit despite herself to see the very Doctorish mannerism carried out by her body. Her smile bloomed into a full-on tongue-touched grin. "What?" he said defensively.

"Nothin'," she replied, " 's just…watching myself be you; it's a bit disorienting."

The Doctor looked her up and down as her smile retreated and she began to nibble at a bit of skin on her thumb. "I know exactly what you mean," he replied.

Rose awakened the next morning to find herself spooning…herself. Well, spooning the Doctor. She shifted a little and threw her arm over him, pulling him closer as she shifted. That was when she noticed it. Immediately she moved away from the sleeping form in front of her. Oh my god! she thought, her face hot and no doubt scarlet at the realization. She had an erection. She froze in bed, straining to hear the shallow breathing of her body beside her. The Doctor was still fast asleep, and she was glad; she wasn't sure which of them would be more embarrassed by this.

She turned away from the Doctor and curled up on her side, a hand cupping her erection over her pants as if to hide it, willing it to go away. After fifteen minutes, it only seemed to get worse, and then to compound the problem, she realized she had to pee.

As quietly as she could, she extricated her long limbs from the bed and moved toward the en suite, careful to tilt her body away from the Doctor in case he woke up. She shut the door behind and locked it. She went over to the toilet and clumsily maneuvered her erection out of her pants. She couldn't very well point it downward in this condition, so she braced her hand on the wall above the toilet and leaned forward, spreading her legs further apart. She stopped for a minute, realizing she'd forgotten to put the seat up and then doing so quickly before resuming her previous position. Her bladder suddenly felt like it was going to burst, and when she was reasonably sure she'd hit her mark, she pushed. Nothing came out. She pushed again, and this time she got results—mostly on the back rim of the toilet rather than in the bowl. "Dammit," she muttered. "Sod this," she said, putting the seat down and sitting, leaning awkwardly to maneuver her foreign anatomy downward.

As she urinated in fits and starts, Rose wondered if this very situation is why the Doctor regularly initiated morning shags. When her bladder once again seized up on her, she shot a guilty glance at the shower and contemplated doing something about this hard on. No, she thought a moment too late as the thrill of arousal at the idea only exacerbated the problem. Rose groaned.

She decided she did need a shower, but not for that purpose. After a few short minutes under the cool spray of the showerhead, she was able to…relax…and exit the shower. Beads of water still coursing down the flat planes of her chest, she tried not to moan with the relief of emptying her bladder, oddly thankful to also be able to maintain a normal stance while doing so.

"Ow!" The Doctor heard his own voice from the next room preceded by a soft thunk.

"Are you alright, Rose?" he said as he entered the kitchen to find her—rather, himself—standing in front of the kitchen cabinets, clutching her—his—eye.

"Yeah, 'm fine," she says, taking a few steps backward and plopping down on one of the chairs at the kitchen table. "Jus' not used to being this tall; or having arms this long," she says, holding out the one not clutching her face.

"You were standing too close to the cabinet when you opened it again, weren't you?" he grinned.

"Shut up!" she shouted as her freckled cheeks flushed with embarrassment.

"Try to remember that that face is on loan, would you? We've still got eleven days, and I'd like to have my face back without dents."

"Keep it up and I'll suddenly decide to shave my head," she said, gesturing at the less-than-perfect juts of his hair atop her head.

The Doctor threw his hands up in surrender, "Alright! Alright, I'm sorry. Let me get you some ice for my eye."

After they settle in at the table with tea, Rose with an ice pack pressed to her borrowed face, the Doctor speaks, "Rose?" his voice is almost meek, "You wouldn't really cut my hair, would you?"

"Of course not."

Rose walked into the kitchen to find the Doctor sitting at the table, eating chocolate cookie dough ice cream out of a pint container. "Are you going to eat all that yourself?" she asked teasingly.

"Not if you want some," he said, offering her the large bite perched on the spoon.

"That's alright," she said, shaking her head. The Doctor immediately pushed the spoon between his full lips and made a sound that was almost sinful.

"I forgot how amazing ice cream tastes, especially this kind," he said around the melting glob of ice cream as he held up the container and gestured at it with his spoon. Rose heard the unmistakable crunch of a bite of chocolate. "It's just heavenly; perfect thing to soothe my upset stomach."

"Upset stomach?" she repeated, "Since when does ice cream cure a stomach ache?"

"Since today, apparently; stomach's been out of sorts all day."

Rose just stared; the Doctor—in her body—sitting there, perfectly tucked into a pint of ice cream, talking about his stomach being out of sorts. A niggling feeling began at the back of her mind. "Doctor…have you been feeling tired today?"

"Yeah, now that you mention it; I had a kip on the sofa earlier where you were at Tesco."

"Oh no."

"Yeah, tell me about it! The couch is not a good place for a nap. I woke up with a hell of an ache in my lower back."

"Oh no," Rose said again.

The Doctor looked at her, dressed in a pair of his denims and his Clash t-shirt. She was staring off into space with a look of horror on her face. When her eyes fixed on him, her expression turned piteous.

"What? Do I have ice cream on my nose?"

"No," she said, her gaze going far-off again as she lowered herself into the seat across from him. Her face started to turn red as she pressed it into her hands.

"Then what's wrong?" he asked, taking another bite of ice cream.

She pressed the heels of her manly, hairy hands into her eyes as she struggled to get the words out. She couldn't look him in the eye. "Doctor," she sighed, her voice dropping to nearly a whisper, "You're…gettingmyperiod."

The sound of his spoon clattering to the tabletop was drowned out by his resounding, "What?!"

Rose finally looked up at him, "You're…getting…my period."

"WHAT?"

"Fatigue, upset stomach, back ache, chocolate chip cookie dough ice cream," she counted off on her fingers, "You're getting my period. Probably starting tomorrow."

"What?" he squeaked, this time in quiet disbelief; he began to grope for the spoon without taking his eyes of her—his—face. He retrieved the spoon and began eating again, this time without joy.

"It'll be alright. They're never that bad. It's only five days," she glances away, and then back again, "I'll show you where the tampons are."

The Doctor choked on his bite of ice cream, "Tampons?" Now he was blushing as furiously as she was.

0~0~0~0

Sure enough, the next day Rose was handing a very-embarrassed-former-Time-Lord-trapped-in-her-b ody a tampon. She offered to show him how to put it in; an offer he balked at before retreating to the en suite and shutting the door.

After a fair amount of cursing in English and Gallifreyan, he opened the door just a crack. "Maybe you could just tell me how?" he said, not quite meeting her eye.

Rose handed him a second tampon, and he abruptly shut the door again. She smirked (and silently wondered for a moment if it was her own smirk or his) and then gave him a verbal step-by-step of the process.

Rose awoke in the middle of the night to the feel of the Doctor spooned up behind her, his breasts pressing deliciously into her back. No; wait. No. Those were her own breasts; nothing delicious about that. That's a whole level of narcissism she has no desire to touch. Except the Doctor's uncharacteristically-womanly hand is cupping her genitals over her pants—his pants—oh damn it this wasn't getting any easier to sort out in her mind, even though they were past the halfway point now.

She wriggled a little, and the Doctor spooned closer, fingers curling gently against her crotch; she noticed with dread that her borrowed body was starting to respond. "Doctor," she whispered.

The sleeping form beside her shifted again, and pressed against her, fingers curling again tantalizingly. The Doctor ground his non-existent erection against her backside, and suddenly all those tell-tale signs of the beginnings of an activity she usually enjoyed in the middle of the night seemed intimidating. "Doctor!" she hissed, and he awoke.

"What is it, Rose?" he said sleepily, still not moving his hand.

"You're…touching me."

He wriggled a little, as if re-discovering where his body and all his limbs lie, his fingers moving carefully over the bulge in the front of her pants. "So I am," her own voice sighed into her ear. "You seem to like it," he says saucily, and she's not sure if it's his flirtatious tone she hears, or her own.

"I…I can't help it," she said, and something in her voice akin to shame or panic or some combination of both caused the Doctor to withdraw his hand.

"I'm sorry," he said softly. He put his hand on the decidedly-safer place of her upper arm, trying not to consciously admire the lean strength of his own bicep. "It's nothing to be ashamed of, you know," he told her. He brought his hand up to tuck her blonde hair behind her ear, but since he was the one with that hair presently, he settled for stroking her temple gently. "Took me awhile to get used to that thing, too; has a mind of its own, it does."

"At least you had one before," she said, rolling onto her back. The Doctor draped his arm over her chest, resting his hand on the flat plane her heart beat beneath.

"I did, yes. But I could control a large number of my autonomic functions, including arousal; after the metacrisis? No."

"It's just…it's weird, Doctor. I don't like this."

"Oh c'mon now," he said soothingly, "As if you've never been aroused by me touching you before?"

"I have a bloody hard on, Doctor."

"And I have a bloody fanny," he grinned.

Rose stifled a laugh. "That's not funny."

"Sure it is," he trailed his hand down her lean torso and hesitantly touched her where she strained against her pants.

She covered his hand with her own. "Doctor," and he withdrew, resting his palm on the trail of hair below her navel, "It's just not the same. Right now, you're…me, and I can't get turned on by me. That's just…weird."

"Rose Tyler," he said with playful reproach, "Do you honestly expect me to believe that you've never touched yourself?" he drew his hand up to her chest and rested it there as he propped his head up on his hand.

"Of course I've touched myself!"

"Then why does it have to be different for you to touch me when I'm like this?"

"Because masturbating and shagging y'self aren't the same thing," she huffs, "and…and I don't like this," she gestures at her crotch, "It…it feels strange. And it's starting to hurt."

"Wellll," the Doctor started, and it was strange to hear that from her mouth, "If you don't want to touch me when I'm like this, does that mean I can't touch you?" he asked quietly.

Rose felt her erection twitch, and damn it, it ached. "No," she said after what seemed like an eternity of silence. Then the Doctor was on top of her, pressing his lips to hers, and while they were her lips, she had never kissed herself, and so was quickly able to focus on the fact that they were lips, kissing her the way her Doctor always had. He nipped her lip. He did that thing with his tongue—her tongue—and suddenly it mattered much less that he had breasts—her breasts—and they were pressing against her chest. He pressed against her, and the feel of a pulsing erection was still between them, only this time, she was the one who felt the strain of it as she got turned on and the relief when the Doctor rocked against it.

"Doctor," she whimpered. Well, she'd meant to whimper, but it had come out of her borrowed vocal chords as a husky plea. The Doctor's lips curled into a smile against her neck and he slowly drew the covers down as he placed kisses along her torso. She knew what he was doing, and the coil low in her belly tightened at the thought. Her cock twitched again. He exhaled against the skin of her stomach, the warm air tickling the hairs.

"Shhh, it's okay Rose; I've got you," he said gently as he drew down her pants. His trembling breath ghosted over her erection and she whimpered—a proper whimper this time—and then his warm mouth was subsuming her.

"Oh!" she cried out, her hand fisting in the duvet for a moment before she felt one of his soft hands covering hers. She turned hers palm-up and he took her hand. Rose jerked her hips up involuntarily, chasing the sensation of his tongue against her shaft, his throat swallowing around her sensitive tip. The Doctor hummed and used the hand that wasn't holding hers to steady her movements.

"Oh fuck," she groaned as he withdrew to circle the head of her cock with his tongue, letting go of her hand so he could encircle her length and stroke it in time to the up-down movements of his mouth. "Fuck," she cried out. "Doctor…Doctor! I'm goin' to…I'm…I'm—" she interrupted herself with a gasp, pulsing her release into his mouth as he continued his ministrations, swallowing her essence.

Minutes later, the two lay side-by-side on their backs. "You're right," the Doctor said flatly, "This is weird," he said, slightly unsettled. "Hearing my own voice calling my name like that; that's…different."

"Good different, or bad different?" she asked, taking his hand.

"Just…different."

There was a pregnant but not uncomfortable pause before Rose grinned, "So, how did you get so good at that?"

The Doctor could practically see her cheeky tongue-touched grin in her tone of voice. "Oi! It's my body remember?" he squeezed her hand and added smugly, "I know what it likes."

Rose maneuvered her tall form into the crook of his arm and found that the swell of his breast made it hard for her to get comfortable. So she readjusted and ended up pillowing her head on both of them instead. As he stroked the short hairs over her ear and she drifted off to sleep, things almost felt normal.

"I had Jake bring this over so I could analyze it. Basically, the gun is calibrated by these toggles here," he points, "and it creates a small energy field that temporarily contains a consciousness in a sort of…bubble…and transports it to the place of the next-nearest consciousness. The settings determine the decay of the energy field."

"The next-nearest consciousness? Then you're sooooo lucky. You were this close to trading bodies with my mum!" she laughed, and it was the Doctor's laugh.

"Oi!" the thought of that even being a possibility made him turn a bit green.

"So why would anyone make something like this?" Rose asked, "Do you think it's because of the laws about the psychografts?"

"Not likely," he grinned with Rose's mouth.

"Then what?"

"Well, it could be a non-lethal weapon to confuse and disorient the enemy, or…"

"Or what?"

"More likely than not, it's a…a sex toy," he blushed slightly and tugged at his ear.

"What?!"

"You know, a way for couples to spice things up in the bedroom?"

"An alien sex toy? Seriously?"

"Yep," he said, popping the 'p' as he set the gun on the table.

"Well then," she paused. "Only…" she looked at her manly, hairy wrist as if checking the time, "One more day to make the most of it, yeah?" she said, tugging the Doctor toward the bedroom by the sleeve of her navy blue hoodie.

Once the Doctor was naked beneath her, she thought she might lose her nerve. It was different from last time; it was daylight, and she could see her own face looking up at her. She was doing the touching. Carefully, she reached between the Doctor's legs and felt moisture. It made her body ache in ways she'd only experienced over the last couple weeks.

Rose tried to ignore the insistent throb of her erection, and instead concentrated on the task at hand, remembering all the things she did to herself when she was alone in her room on the TARDIS, struggling to find release after a day of flirting and just-hand-holding with the Doctor.

She quickly found a rhythm, and was rewarded with a hitching of the Doctor's breath. She shut her eyes and tried to focus on his breathing and the movements of her hand as her fingers rubbed circles into his clit. The Doctor was trembling beneath her ministrations, and after several minutes, she knew he was close.

When the Doctor came, it was loud and extremely…womanly. As he came down from his peak, he muttered under his breath in Gallifreyan, and Rose was once again hit by the strangeness of this situation; hearing alien words from her own lips.

Rose ran her long, slender fingers down the Doctor's slit and carefully sank two of them inside of him, making him whimper. She thrust them in and out a few times, lazily curling her fingers against the spot inside that she was very familiar with. The Doctor keened beneath her, "Please, Rose," he sighed, and the Doctor was right, what he'd said the other night: hearing her own voice call out her name like that…it was strange.

Shaking off the last vestiges of bashfulness, Rose withdrew her fingers. Quickly the Doctor took hold of her wrist and brought her slick digits to his plump lips. Rose closed her eyes again, imagining that her own lips were his lips, because watching him lick his own fingers after they'd been inside of her always made a thrill run through her. As she reclaimed her fingers and pressed herself fully against him, she claimed his lips in a bruising kiss, an insistent thrust sliding her cock along his wet slit.

"Need you," she whispered against his lips.

"Want you," he replied.

Rose slipped a hand between them and fumbled with her length. She struggled for several moments to find the right angle until the Doctor replaced her hand with his own and brought her to the right place. She pushed carefully inside, groaning at the heat, the slick, and the way his muscles squeezed her. After they both had a moment to adjust, she began to move. "Oh fuck," she whimpered into his shoulder, "Oh God. Oh…oh Doctor…this…this is…I…" she trailed off and simply covered the Doctor's mouth with her own, losing herself again in the motions of his tongue and the familiar way his unfamiliar lips moved.

She broke the kiss to nip at his neck, and he groaned, "Rose. I'm close. I'm close; I can feel it. Help? Please?" he pleaded. In response, she slid a thumb between them and worked his clit. He panted and trembled beneath her, and Rose felt his walls tighten around her cock.

"Come, Doctor," she begged. She was so close to her own orgasm, and she didn't want to let him down, "Come, come, come," she whispered against his neck, "Please." With that, her orgasm crashed over her, and it was then that the Doctor came, his fingernails digging into her back as she emptied herself inside him.

She collapsed on top of him, spent, a sheen of sweat slicking the space between them. Her chest rose and fell with her breathing, his breasts pressing to her with the movement as he stroked her back in the same way she did when they did this normally. "I love you," she whispered.

"I love you too," he replied.

The next morning, they awoke as themselves.

The next week, Jake pointedly didn't notice that the strange alien artifact had never been catalogued as inventory in the Torchwood storage facility.