The Doctor crossed his arms and tried to whack some warmth into them. Snow fell in great clumps from the oppressive clouds above their heads and clung to his jacket like moss mottling a stone, before seeping through and drenching his shirt. He was soaked to the skin because the snow didn't even have the decency to be powdery.

River had offered him one of her layers, but having already turned her down in an act of astoundingly ill-judged chivalry, he wasn't going to ruin it by asking her for one now. And it didn't look like she was going to offer a second time either. He looked at her tucked up in layer upon layer of warm waterproof clothing, and a rather fetching fur hat, and he bristled with envy. She smiled benignly back.

His feet kept sinking into the gathered snow and he was fairly sure his boots weren't going to recover. She, on the other hand, had snow boots — why did she have to always be so annoyingly well prepared? She could at least have warned him he'd need to bring a parka when he came to pick her up. He knew what she'd say to that — 'Why didn't you run your environmental checks?' Blasted woman had an answer for everything.

He had a niggling feeling they were going back in the wrong direction, but he said nothing because he knew that the moment he spoke, the TARDIS would appear from out of the snow and fog and he'd be wrong. Better to take longer getting back than that. And this way, if they were in fact lost, he still got to say, 'I knew it!'

They rounded a large snow-covered rock and found its far side dry. River's eyes lit up as she looked past it and saw pillars of steam winding up out of a geothermal pool. No, he thought, she's not thinking of swimming now, not when I'm about to die of frostbite? He knew the answer even before she began to shed her layers. There was no point in arguing with her or even glaring at her; she'd clearly made up her mind already.

He leaned against the warm volcanic rock trying to steal some of its heat for himself. She had herself stripped bare in record time, inhaling sharply as freezing gusts of wind buffeted her and large snowflakes patched her goose bumped flesh. She was probably just going to hop in without even testing the temperature. Reckless.

Then again she had probably calculated that it was thirty-eight degrees Celsius from the temperature of the surrounding rock and the rate of steam generation relative to the eighty-six per cent humidity of the surrounding air, like he had.

She didn't jump; she stepped in like she would a hot bath, gasping with each step that brought her deeper until her shoulders were submerged and her skin smoothed by the warmth of the water. He stood shivering, watching her with what he could have sworn was a frown, but her beatific smile in response made him wonder how it was coming across on his face.

She was swimming in a petri dish — he hoped she knew that — the perfect environment for bacteria to thrive: water at body temperature. If he pointed that out, she'd only tell him that the acidic pH of geothermal pools prevent the flourish of algae and bacteria. And if he warned her about acid-resistant strains, she'd only remind him that acid-resistant strains aren't harmful.

She swam across to the other side. Breaststroke he noted: a blatant invitation for him to join her if ever he saw one. Well she could forget about that. He stepped away from the rock and watched her treading water, snow settling on her wet hair as she smiled up at him.

What would be the point of getting in to join her? They'd only have to get out again and freeze as they tried to get dressed without towels. Then they'd really be in trouble. He'd say it too, but she'd tell him not to be such a fuddy-duddy and that the TARDIS was right there on the other side of the pool, parked with its back to it, obscured by the steam.

There was absolutely no point in arguing with the infuriating woman at all; she always found a way of winning. The best he could do was to make it seem like it was his idea. He peeled off his sopping clothes and she raised an eyebrow and grinned, delighted, before floating on her back to catch the snow on her face and chest. He slipped into the hot pool, the water loosening his aching joints and warming his temperament as he swam across to her.

The argument he could skip, but not the making up.