The wind is cold on his face. He stands quite still, unaware of how long he's been here. The chips in his hands are cold, rain come and gone, and he just stands, staring.

His smile is wry in the growing dusk as he tries to remember a time when mourning hurt less. Was it right to mourn someone who wasn't even dead?

"Hello," he says emptily, swallowing and glancing over the top of the stone slab to the other hundreds that were laid out here, peeking out from the ground like shy children. Humans were funny, gathering their dead and sticking labels on them, labels with short, inconsequential definitions of the people they weren't. 'Devoted father'. 'Caring mother'. 'Beloved'. It's all very alien.

He lets his eyes drift mournfully back in front of him, only a few words etched into the stone. After the battle of Canary Wharf there had been no one else left to oversee the making of a grave. Despite not being human and generally not a part of the culture, the Doctor had felt it somewhat his duty to do this for her, to make sure she was never forgotten in this world. Who else was left to do it?

When asked what he wanted the inscription to say, he had been lost for words. What could one possibly say? Eventually he had settled on eight. Just eight. Eight words to sum her up. It hardly bares thinking about.

She gave her life to save the world.

Add in a name and her date of birth (he positively refused to label her date of death), and here she is. The closest thing to a 'Rose Tyler' he has in this universe, sitting bleak and cold right in front of him, living out the remainder of her life in a graveyard.

"You never wanted to go back," the Doctor remarks, staring at the curves of the letters as though willing them into a picture of her. "Always choosing me, the 'better life', over your own family, your own flesh and blood." Something in his gaze turns cold, like milk souring overnight. "Was it worth it? Was I worth more than the people who birthed you, raised you, loved you?" He's met with silence, and a cold wind kicks up around him. He lets out a dry laugh through his nose, and he drops his gaze to the floor, to the winter grass pale and sickly from watery sunshine. "I didn't think so."

"Er, hello," says a voice from behind him and he starts slightly – there isn't supposed to be anyone here. Martha's visiting her family, and he knows there aren't frequent visits to this cemetery.

But there's something in that voice that's hauntingly familiar and, as he turns, he's not so surprised to see him – an old him – with an old TARDIS right behind him. The Doctor feels himself pale.

"Routine check-up," the old him continues, with no idea to who he's currently speaking, "of disappearing and reappearing police boxes. Nothing to worry about, just a little paranormal that we're all sorting out. No worries. Honestly, you haven't seen me."

The Doctor blinks, remembering this scenario from a very long time ago; but he watched it through different eyes back then. Through cold and blue instead of warm and brown. He used to be so different.

"Uh," he stutters, clearing his throat. He must be careful not to give anything away. "Yes. Right. Check-up, I see. Won't say a word. Promise." He can't help a grin, though it feels so false in light of the grave he's right in front of.

His ninth self turns back, seemingly satisfied, and only then does everything fall into place. That voice he heard, so long ago, the reason he went back for Rose a second time... it was him. He intervened with his own timeline, with history, to make himself go back for her. And... if he doesn't, now – if he doesn't tell himself – then Rose will never travel with him. She'll never get hurt, she'll never be ripped away from the universe where she belongs and she'll be safe, happy.

But he can't do that. He knows he can't. He'll be the last to cause a paradox. So, his shoulders dropping, the Doctor locks on to the telepathic field of the TARDIS and sends a message back to his old self.

...Go back for her...

The old him turns, his face hard, and he's frowning like he's suspicious but doesn't know what of. "Excuse me?"

He thinks he's just a human, the Doctor remembers, so his has to feign ignorance to that, too. "Yes?" he asks simply, eyebrows slightly raised – he always was a good actor.

His ninth self frowns harder. "Did you just – did you just say something?"

"Well, I... I don't know. I said I wouldn't... say a word, but..."

This feels a little stupid if he's entirely honest with himself, but the conversation plays out exactly to memory, like it's been scripted and waiting for him all these years.

"No, no," the other him retorts impatiently, "after that."

The Doctor raises an eyebrow. "I didn't... say anything..."

"Right," says the other him, evidently not quite believing him. He remembers not believing him, and he's glad he's finally got the answer to the puzzle. His ninth self gestures vaguely to the gravestones. "I'm sorry."

The Doctor nods sagely, his breath shallow. "You're bound to be," he says quietly.

"Right," comes the confused response, his ninth self bristling, "well. Er... Have a nice day. Cheerio."

Without another word the old him disappears back inside his TARDIS, and the engines groan out of existence. The Doctor lets out a heavy breath, casting a look down to the gravestone beside him. He gives a wry chuckle. Things are hard without Rose, yes, but at least he has the comfort of knowing that somewhere – out there – an older him is just about to enjoy the adventures with her all over again. It fills him with a strange kind of warmth.

When he sees Martha not long afterwards there's a smile in his actions he hasn't felt for months.

"Something's cheered you up," she says casually as they walk, shoulder-to-shoulder, back to the TARDIS. The Doctor smiles.

"Yeah," he replies, glancing up to the night sky where the stars twinkle down at him. "It has."