When she thought about it, it never ceased to amaze her. No matter how many millenia had passed, nor how far they'd flown out amongst the stars, they'd carried it with them. Once every year, whatever that meant wherever they were, in the midst of the darkest days of the solar cycle, the children of Earth celebrated with lights and music and hope. An annual victory over the darkness, the promise that life and light would return.

Conifer trees were shipped across thousands of light years to decorate outposts on arid desert planets. Tiny lights shone from the view ports of ships, competing with the blazing stars of space. Songs poured from every speaker, their ancient lyrics virtually unchanged from those she remembered.

Luna University, washed in the rays of Sol herself, knew no natural darkness. Instead, the university celebrated along with Earth. As December approached, evergreens sprang up across campus, sparkling with red and green and gold, lighting every dark corner. Constant reminders of the Christmas trees of her own childhood.

The purely decorative artificial tree in her foster home had gone up like clockwork every December, the presents beneath it a mere discharge of duty. However, it was the Norway Spruce which stood in the Pond's sitting room which had always felt like hers. Generally a bit lopsided, a kaleidoscope of conflicting colors, fragile family heirlooms hung from its branches next to simple childhood offerings composed of Popsicle sticks and felt and glue, her own mingled with Amy's. And beneath its branches, she would always find several presents with her name on them. True gifts, neither expected nor required. In that, at least, she knew now she might have been more fortunate than other children for whom there was never a clear difference.

But it was the smells which rose up from the university kitchens, permeating the wood-lined corridors, which brought back the strongest memories. Bright sun-filled afternoons sitting with Amy at her kitchen table as her mum brought forth tray after tray of warm biscuits from the oven. Gingerbread men and macaroons and burrebrede baked from Mrs. Pond's own mother's secret recipe.

Only there would be no homemade Christmas biscuits for River this year. No presents under the tree. In fact, her only tree was the small one she'd finally broken down and and put up in her small sitting room. She'd almost decided not to decorate at all, but in the end realized not commemorating the season at all would be worse then celebrating alone. And the tree, which reminded her of the pathetic stick in that cartoon shown on the tellie every year of her childhood – all her childhoods – echoed her mood perfectly.

Not that it was all bad, of course. There were concerts and carol sings and a gift-exchange amongst the first-year archeology students. She helped string popcorn for the common room, staying up far too late and getting drunk on port wine. When they finally managed to hang it about the room, late the next day, the primitive garland contrasted sharply with the view of Earth outside the windows.

Still, when talk turned, as it inevitably did, to holiday plans with families, River remained quiet. Not that she was even alone in that, of course. Not everyone had families to go home to, nor did everyone even celebrate Christmas. But still, she did. Sort of. And it was that empty space where home and family and a proper Christmas should have been which echoed hollowly inside her.

It was on Christmas Eve, returning alone to her darkened rooms, the sunlight streaming outside muted through night-tinted windows, when the loneliness struck the hardest. When the glow from her small tree seemed to mock rather than warm. The longing for what she'd had, for everything she'd never really appreciated when it had all been right there in front of her, ached through her. She fled to the window, letting her gaze travel out over the dust swept lunar surface and up into the star strewn universe beyond. Out there – somewhere, sometime – her family waited for her to come and find them. For her to find herself. Only then, strangely comforted by this reminder of her own small place in the vastness of space and time, was she able to move to her bedroom to find the welcoming oblivion of sleep.

River woke late the next morning. Christmas morning. Not that it mattered, for she had nowhere to be and nothing to do anyway. Getting out of bed, she threw on her dressing gown and padded into the sitting room to find some tea.

And froze in the doorway.

Her tree was still there, moved to the small table. And in its place, an almost unbelievably large brightly decorated evergreen filled half the room, colorfully wrapped presents sitting beneath it. She couldn't even begin to imagine how anyone had managed to fit it through the door.

And then she started to laugh. Because...of course. It was as good as a signature. If the Doctor even had a signature.

She stepped across the small space remaining in the room and knelt down before the tree. One package in particular caught her eye. Or, more accurately, her nose. The smell of freshly baked biscuits emanated from the red and green metal tin, instantly recalling every happy childhood Christmas memory. And though she didn't even have to look inside to know what she'd find, she popped it open anyway.

Gingerbread men and macaroons and her grandmother's unmistakeable burrebrede.

Love in a tin.

A photograph lay on top of the biscuits, Amy and Rory standing in front of the TARDIS, his arm around her shoulders. Red Santa hats perched on their heads; a sign in Amy's hands proclaimed in large block letters, "Happy Christmas, River!"

She traced the familiar faces with her fingertips and smiled. Suddenly, time and space and the universe itself seemed much smaller. And she herself, infinitely less alone.