He waits.

He gives their apologies to Vastra, parks the TARDIS out of the way on a cloud - well, technically, super-condensed water vapor - at Vastra's insistence, and pretends that River's just running a little late.

He pulls out his old cot - River's cot - his children's cot. The pain of that always steals his breath for a moment. But he's so old now, and it was so long ago that he lost his children, his granddaughter. Their memories and faces were locked away safe in his too full head centuries ago. But to have a new little Time Lord laying there - a child with River...

The Doctor blames the dust stacked across the ancient wood from a dead world for the sudden wetness around his eyes. After that, he keeps himself busy designing the perfect nursery adjacent to their room, and he keeps his eyes away from the cot set up in its place of honor. All the stars in the universe shining through the small mobile to reflect across the TARDIS blue ceiling and walls.

There's a couch for long nights and twin rocking chairs for River and him, adjacent to the soft blue flame of the harmless starflower flame from Ezerbaf'af, with its muted heat and soft shadows. He even braves Amy and Rory's old room to rescue the TARDIS model and dolls that Amy so carefully molded as a child. Then he shuts the door carefully, telling himself that it's a surprise for River. That it's not a tomb.

River will come.

The cavernous pit between his hearts knows better.

Then he hears her message - caught by the TARDIS answerphone while he was out saving the universe with Vastra, Jenny and Strax.

His finger shakes as he presses play.

"Hello, sweetie. Couldn't be bothered to answer your phone? Typical. Doctor - a last-minute offer has come up. I can't turn it down. Now don't fuss - I expect you to meet me there. I promise not to dive off any buildings in the meantime. Besides - it's a Library. Safest place in the universe. Got to dash - I'm graduating my last few students before I run off into a mad blue box with my husband. I'll text you the details."

The line goes dead, and that's it.

All the breath whooshes out of his lungs in one horrible rush, as though the air around him is suddenly toxic and choking him. His hands come up to his neck as he sinks to his knees and tugs desperately at his bowtie - undoing it and flinging it to the floor. His fingers tremble over the buttons of his collar and it rips as he yanks it undone.

He's gasping at great lungfuls of air, and it's only then that he realizes he's sobbing. Hands clutching uselessly at the unyielding metal floor of his ship as she whirs and hums in sympathy. The Doctor is sinking in on himself, aged a thousand more years in that instant, he can feel it in his bones and hearts and soul, the pain so much worse than any damage the Master could have ever imagined.

He doesn't get up again until Vastra sends a search party. Even then. She bangs on the door for so long - with Strax threatening grenades - that the TARDIS herself lets them in.

As Jenny and Vastra help him to his feet, weak and wobbly, the Doctor's eyes fall on his discarded bowtie. The one from their first wedding. The one from that last night. His anniversary bowtie. "She's not coming." And he wrenches his eyes away.

Jenny and Vastra exchange a look over his head, but they don't ask him to elaborate. For that he is thankful. For once, the Doctor doesn't have any words.

As a matter of fact, he doesn't speak again for weeks. Maybe months. Time doesn't matter anymore. He purposefully lets it slip through his fingers. It doesn't matter. He doesn't care.

He'll wait anyway. As long as it takes.

The universe owes him this. It cannot possibly be so cruel. But he knows it is. The one lesson he has learnt over and over again. He knows it better than most.

He thinks for one aching moment of the children they could've had - should've had - with River's magical time-head of hair and eyes and his - well, hopefully they'd take after River, at least for the first regeneration. His hearts ache and twist even more at the thought.

He'll wait.

Right here. On this cloud. In London. In 1890. Where she promised she'd find him.

River would do it for him. It's the best he can do. And he knows it's a poor imitation of when she stopped time for him, but he doesn't know what else to do.

He's afraid to set their personal future in stone. To go to Luna University and find her already gone. To go to the Library and find her already there.

How can he go there? If he doesn't go to the Library, then maybe he's wrong. Maybe she really is still out there - just running a little behind. How can he see his wife there - how can he face her there and know what they've lost? What he never thought they could have but suddenly wants more than anything in the universe?

She will come. She'd promised.

You'll hardly have a moment to miss me.

He misses her every single moment. With every breath his bones ache with missing her. Hidden away on a cloud, the Doctor holds his breath: waiting.