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It would be so easy, to steal a few more moments with her.
There are so many ways he could do it; so many times he left her alone. When she'd been exploring Satellite Five with Adam, or investigating Florizel Street in that magnificent dress. When he'd been busy with Reinette or when he'd been teaching a class at Deffrey Vale. A thousand and one opportunities to track her down. He could go to any of them or all of them.
He'd burnt up a sun to say goodbye. What's bending the rules, just a little, in order to say hello?
He'll see her before she sees him, because that's how they work. Her back will be turned and he'll come up behind her, and he will murmur "Rose," and she'll just... know. She'll see right through him and she'll recognize him, because she's always done that. Known him. Knew him before he knew himself, really—had known that there was a dorky, love-struck goofball lurking under his scowling brow and leather armor. Understood how to bring that out in him, until it was so obvious he'd had to change his outsides to match his insides.
Before he has the chance to say anything else she'll be hugging him, and it will take him a moment to figure out how to hug her back, his arms waving lamely in the air. He's grown used to hugging Amy, who is so near to his height—forgotten how very small Rose was. Is.
There will be tears in her eyes when she takes a step back, which will throw him, though it shouldn't. "Oh, but… you're so young," she'll say, her voice warbling and cracking just the tiniest bit at the end.
His gaze will grow sad and fond as he takes her in—eyes open and trusting, hair short, wearing a hoodie and not a leather jacket. (Only now does he realize where she must've gotten the idea.) "So are you," he'll say, then clamp his mouth shut as he realizes how dangerous it is to give her a hint like that.
And so—partly because he's scared of what will come out next if he doesn't, but mostly because he wants to—he will kiss her, once, softly. Then twice, and again, and she won't ask questions because she knows the rules and knows what he needs. Her kiss in return will be quietly lovely, tentative but more sure with each passing second: like trying to sing along to something you'd once known by heart.
(So when he gives her—gave her—away on a beach to another man with his face, she'll be free to make her choice without guilt: knowing that in his life yet to come, he will have these moments with the girl she once was. That in time, everyone will get their fairytale ending. Not a happily ever after, perhaps, but the chance to be awakened with a kiss.)
"I should go," he'll murmur softly, leaning his forehead against hers with his eyes squeezed shut, wanting nothing more than to breathe in her air a little longer.
"Okay," she'll whisper back, and their noses will bump as they pull away, shy and awkward. It will be this, more than anything else, that breaks his hearts—that he'll never get the chance to learn how to be near her in this body. He doesn't think he'll ever have hands that won't fit hers, but these things take time, and that's the one thing they seem to be perpetually running out of.
Steeling his resolve, he'll crush his lips against her temple and turn to leave. And that should be that… only at the very last second, as he's walking away from her (never her walking away from him; not ever) she'll run to catch him up, spin him around and kiss his cheek, chastely. When she pulls away, her hands will somehow already be busy adjusting his bow tie.
"I'll bet I miss you," she'll say with a quirk of her mouth, a frown twisted into a smile because even when she's talking about herself she manages to put him first. She'll pat down his collar and run an experimental finger down the length of his right brace—pulling at it, checking its elasticity. (Never one to leave a limit untested, Rose Tyler.)
And he'll open his mouth to say either "I hope so" or "I wish you wouldn't," or maybe "quite right, too," but before he can decide which is the worst lie, he hears—
"Doctor? Are you with us? You spaced out there for a second."
"Right! Yes! Sorry, Pond. Where was I?"
He'll find her tomorrow.