The Doctor thought he'd check on River Song. They'd only met the one time by her timeline - as far as he knew - but that meeting had been... eventful. Let's see... she had been trained her whole life to kill him. She'd helped with locking Hitler in a cupboard, been killed, regenerated into River Song, beaten up some Nazis, killed him, been told... what he'd told her... to tell River Song, found out she was River Song, given up her remaining regenerations to save him, awakened in the best hospital in the universe, and been given a time traveler's diary. Busy day. Even by his standards.
He'd met her since then - most notably at their wedding - but she hadn't yet met him again. Or would not have yet met him again. Or something. He understood it instinctively, but when it came to thinking about the details consciously, well... he was inclined to let the Old Girl handle it. In any case, it should/will be safe enough to have a look in and see how she was/is/will be doing. If he knew/would know when/where she was/is/will be now/then. He frowned to himself and decided to stop trying to puzzle it out in English; human languages hadn't the vocabulary or the maths.
"You understand it though, don't you, Sexy?"
The bleeps and whistles seemed to indicate that yes, Sexy did understand it. "Right then; I don't know where she is, but you do, so can you take me to her?" More agreeable bleeps and whistles. He grinned to himself as the TARDIS dematerialized - he'd look in on River, make sure she was all right - and then get out before she spotted him. No sense in blurring the timelines, but he wanted to see her.
He hadn't counted on the TARDIS materializing nearly in River's lap.
Well, just across the room. But it was a small room. And when he opened the doors and stepped out, expecting to catch a glimpse of River across a field or something before closing them and leaving again, he suddenly had a lapful of River Song as she hurled herself at him, toppling him to the floor of her room. His arms tightened reflexively around her as she kissed him, rubbing her lips against his mouth and running her hands up and down his arms. "And what sort of time do you call this? What good is a time traveler who's always late? It's been months since I saw you last!".
"Er... when was that, exactly?"
"Oh, you know," she said breezily, "Changed into this me, killed you with lipstick, brought you back, woke in hospital... " she trailed off, suddenly looking a little uncomfortable. "You don't hold any grudges, do you? I mean, I was sort of brainwashed, and I did make it right after..."
He smiled at her. "No grudges. Not against you at any rate."
"Oh, good!" And she fastened her lips to his, hands fisted in his hair, squirming in his lap and making him very uncomfortable.
She's so... so much herself, so very River Song, but sweeter than when I knew her, he thought, so sweet. His hands wandered up her back into her amazing hair of their own accord and he groaned. This isn't right... she's not my River. Not yet. He broke off the kiss, breathing hard. "Er... River, this isn't... I was just checking in on you, making sure you were all right, and I didn't... I don't want to hurt you... and this... it's not..." and it was his turn to trail off, as she put her fingers to his mouth, suddenly very serious.
"It's all right, Doctor. I know you can't... you feel like you'd be taking advantage of me. You wouldn't be. But it might take some time to convince you. You have plenty of that!" And she was all impish sexy playfulness again. "So. Why don't you take me out somewhere - there are tri-dee movies on this mudball - and we'll... we'll date each other."
He smiled at her. "I've better things to show you than tri-dee movies. We've got the universe".