The first time Rose hears him use a curse – one that isn't what the hell or damn, which, when compared to the sort of things she was hearing on the estate when she was still in primary school, hardly qualify as profanity – she's so surprised she nearly drops a plate.
She's in the kitchen of her little flat, putting away the dishes after finishing some washing up, when there is a sound like a firecracker going off from the vicinity of the dining table. It's quickly followed by a voice that is unmistakably the Doctor's, angrily muttering "well, that's just fucking wizard."
The minor explosion doesn't faze Rose in the slightest. The curse, however, has her whipping around as if physically pulled towards the source of the sound.
The Doctor is seated at her small, round dining table. He's sucking a slightly singed finger into his mouth and glaring at the half-built casing for the TARDIS coral that has slowly but surely taken over the space, in the two weeks or so since they came back from Norway.
"What–" Rose swallows the shrill tone that threatens to creep into her voice, the one that makes her sound uncomfortably like her mum. "What did you just say?"
The Doctor looks utterly nonplussed. He gingerly removes his finger from his mouth to say, "What do you mean?"
"I just–" Rose haplessly waves the plate she's holding, and the water droplets she hadn't quite gotten to drying off yet go flying in his general direction. "I've never heard you swear – like that – before." She can feel heat creeping up the back of her neck, suspects a flush might be making itself apparent on her cheeks, and that's just ridiculous. She's a grown woman. It's nothing she hasn't heard before. It's nothing she hasn't said before. She's said it in front of the Doctor, even – this one and the two-hearted one, back when they were traveling together – and he'd hardly even seemed to notice.
But there's something about hearing it come out of his mouth, about listening to that familiar voice curl around the hard syllables, that sends a hot sort of thrill right down Rose's spine.
She wants him to say it again. Only she wants him to gasp it, wants to hear it come out desperate, breathy and strained – preferably while she rakes her nails across his skin.
They'd drawn very careful lines, back in the old days. They'd built walls and grown hedges around the things they didn't talk about and the thoughts they didn't act on. Those barriers are broken down now, though, weakened by years spent miserable and apart, and she and the Doctor are still tiptoeing around in the wreckage, trying to decide how to go about putting things back together.
Now she's said I love you and he's said I love you and they've had one – just one – absolutely fantastic snog, and Rose is beginning to wonder if it's worth it to put any of those walls back up at all.
"Oh." The Doctor seems to realize what she must be reacting to all at once – and if Rose herself is blushing, it's nothing compared to the flush of scarlet that blooms on the Doctor's face. "Oh. Sorry, it's just–" He gestures helplessly at piece of TARDIS coral that's humming softly on the kitchen table. "The TARDIS is – was – a bit of a prude, really. Never did translate swearing, even when I did it in English. She's just not big enough to do it anymore." He pats the bit of coral on the table, forlornly, and studiously avoids meeting Rose's eyes.
Rose just stares at him. "You mean – you were swearing, all that time, and I just never heard it?"
He does look at her then. "Over nine hundred years, remember? I think you can assume that at some point I've picked up a bit of colorful language."
It comes out sounding a bit condescending. Ordinarily the tone would annoy her, but at the moment all it calls to mind is a different voice, with a different accent but the same speech pattern, saying I think you can assume at some point I've danced.
Besides, even if he is being a bit rude, the Doctor's also giving her this absurd sheepish grin, all twisted lips and near-embarassment, and it snaps something that's been building between them for ages, since long before he had one heart.
Rose makes a decision.
She puts down the half-dried plate she's holding, leaving it to drip on the counter, and crosses the room to where the Doctor is still sitting at the kitchen table. His expression is questioning, grin fading and eyes narrowing in confusion, as she insinuates herself between his legs where they're sprawled on the high-backed kitchen chair.
Looking down at him from her standing position, Rose tangles her fingers in his hair and tugs, draws their faces close together so that when she speaks the words ghost across his skin.
"Say it again."