A/N: This is the closest thing to smut I've ever written. Haven't given this a specific setting; it's just fluff, happens after some nameless adventure, when the Doctor is still fairly early in their time together (but not too early). Oh, and for the record, I don't for a second believe they are actually all back-to-front; there are too many inconsistencies with that logic. Written another fic about that, but that's not this fic. THIS fic is just a short little piece of sexiness I couldn't get out of my head...and I like to leave the ending up to the reader's imagination. ;-)

River burst through the doors ahead of the Doctor, hands already working the controls as he yelled, "River, get us out of here!"

"I'm on it, sweetie!" she called back over her shoulder, never stopping in her movements, and by the time the door had slammed shut behind him, she had sent them into the vortex. She whirled around to look at him; he hadn't stopped running, so used to flying himself out of sticky situations that he was already at the console, and his hands flailed uselessly for a moment when he realized that River had done all the work for him. They stood in silence for a moment, breathing heavily. Then, at the same moment, they both burst out laughing.

"Did you see the look on his face?" River panted in between laughs, one hand supporting her weight against the console while the other pointed back towards the door. The Doctor laughed again and stepped forward, taking her face in his hands.

"River Song, your are bloody brilliant! Absolutely magnificent!" he exclaimed, and he kissed her. It was meant to be a short kiss, a congratulatory, well-done-you sort of kiss, but it lingered for just a fraction of a second longer than it should have. He pulled away briefly, his grin addled a bit, adrenaline rushing through his veins, and before he knew what he was doing, he was kissing her again, longer this time, and deeper, and suddenly his hands were grasping her around the waist, pulling her closer than he'd ever held her before, feeling the slick satin of her dress underneath his fingers...

They broke apart, both gasping, and he began to stutter, "Oh! I'm...I'm sorry, I don't know what came ove-"

He was stopped mid-word by her lips crushing hungrily against his; her hand was at the back of his neck, pulling him in to her, her other arm wrapped tightly around his waist. The kiss was dizzying, and, without knowing how they came to be there, he realized he had her pressed up against the console.

"River," he gasped, breathless, as he tore himself away again. "River, we haven't...I mean, I haven't..."

"Oh, shut up," she muttered, lunging in again, but this time he stopped her with his hands firmly on her shoulders.

"River," he said again, and there was a tenderness in his voice that made her stop. They had done this before in her timestream, of course, and she was at a point in her time frame when she realized they weren't a strictly back-to-front as he had once suggested they would be. There was no real fear for her that this would be their last time together (although it was always a possibility, being married to a Time Lord). But something about the way he was looking at her, eyes full of love and desire, made her stop and listen.

"Sweetie?" she questioned breathlessly, and he smiled that boyish, lopsided, loving smile that made her knees go weak.

"I...I don't..." he stuttered, still not quite grasping the words he needed. He sighed, then ran his hands gently down her bare arms. "I'd like to do this...properly."

Her hearts melted; oh, but he could be an impossibly sweet, gentle man sometimes! She smiled softly and gave a tiny nod; to be honest, she wasn't sure what 'properly' meant for him, but she was willing to be patient and find out.

He seemed to take the nod as permission, and his eyes traveled away from her gaze and down the length of her body, taking her in, and her breath hitched slightly; it wasn't the first time she'd seen him look at her like this, so reverently, but it was the first time for him, and that meant something.

Slowly, carefully, his hands moved from her arms to her waist again, resting for a moment against the innermost curves before sliding gently down to the outward swell of her hips. She swallowed, breath quickening again; the way he was studying her was somehow incredibly erotic. He slid his hands as far down the outsides of her legs as they would reach, then brought them up again until his palms rested against her rib-cage just under her breasts. He paused, eyes flickering briefly to her face, and he seemed to take her parted lips and darkened eyes for permission. Slowly, he cupped his hands over her breasts, thumbs brushing over both of them lightly, and she closed her eyes at the sensation. Before she could open them again, his mouth had covered hers. The contact only lingered for a few seconds, and she let out a soft, involuntary moan when it was broken, opening her eyes to watch him once more.

He was continuing his exploration; his hands had, regrettably, moved from her breasts down to her waist again, then continued around to the small of her back. Over her bum, down the backs of her thighs...and then he was kneeling before her, his hands never breaking contact with her body as they continued down her legs. The red satin dress came down to her ankles, and the ensemble ended in a pair of matching stilettos. There was a slit in the dress on her left side, a dangerously high slit, and as he traveled lower, the fingers of his right hand slipped through to her leg underneath. She shivered, and he glanced up, and oh but she did love the way his forehead wrinkled when he looked up at her like that. Silently, he took her left ankle in both his hands and lifted it; her hands were supporting her against the console, since even if he hadn't just raised one foot of hers off the floor, she probably couldn't have kept her balance on her own now, anyway.

Gently, he placed her foot on top of his thigh, causing her knee to bend and the fabric of the dress to fall away from her leg. She was trying to be still for him, trying to let him explore her the way he wanted to, but her breath was quickened and she couldn't completely stop her legs from trembling as both his hands made their way up her bent leg at a maddeningly slow pace until his fingers brushed the fabric of her knickers.

He stopped with a slight jolt, as if coming back to himself, and after another quick glance at her face, ran his hands back down to her ankle, gently placing her foot back on the floor. He got to his feet and cupped her face in his hands once more.

"Absolutely magnificent," he breathed before capturing her lips in his own. She melted into him, the only man in the universe who could make the indomitable River Song go weak in the knees, and he bent down to hook an arm under her knees, carrying her deeper into the TARDIS.