The Doctor wasn't exactly sure what he wanted to do. He could either escape from the broom cupboard River and he had been forced to hide in, or continue to enjoy his wife's wonderful mouth.
He was a bit ashamed to think that it wasn't kissing that was making him feel so blissful. Oh no, for some reason, River was using her mouth on him in a way that was positively sinful on so many different levels.
He wasn't even sure how it had happened, for crying out loud! (Which he was trying to refrain from doing, lest they be recaptured.) One minute they had been running down the corridor of an ancient castle that was somehow still perfectly intact within the walls from some very angry Tronaeians, and the next they were hiding in a tiny closet with his wife's hand down his pants. That had been about five or six minutes ago.
His fingers were tangled in her hair, not to direct, but simply because he adored the feeling of his skin sliding against the mass of gorgeous hair. He wouldn't call it a hair fetish, because only River's really caught his attention. Maybe it was a River fetish.
Coherent thought was forced abruptly out of his mind when River ran the flat of her tongue in a zig-zag pattern up the length of him. She was far too good at this. He hoped it was because he was very receptive of it in the future and not some other reason. No, the thought of River Song with anyone else made him feel sick. The only sounds escaping his mouth, though, were tiny little whimpers of pleasure, accompanied by the occasional moan.
Her tongue. She would probably be terribly cross with him if he passed out and collapsed on top of her, so he braced himself against the wall of the cupboard. Her tongue should be illegal. His hips started to stutter in awkward thrusts, and he felt the familiar burn spreading from his abdomen to the rest of him.
"Riveeerrr... Oh god, you've got to... Oh, oh, River, I'm gon-"
Then he couldn't contain any longer. The fire raged through him and he unwittingly cried out her name in Gallifreyan. But she didn't move. Not until he slumped back against the wall he'd been bracing himself on, breathing harder than running ever made him. And when she kissed him, he could taste himself on her lips. He tried to kiss her sufficiently enough to prove that he was oh so happy right then, but he couldn't get his mouth to work with his mind properly.
Once they were back on the TARDIS by way of Vortex Manipulator and he was slumped into the jump seat, breathing still a little ragged, he muttered, "You are in so much trouble later, Doctor Song."
A/N: it's not quite smut but it's not remotely clean... I don't know what to classify this as. And no the castle isn't Hogwarts. Not really.