Every year on his birthday, the Doctor paid Earth a visit. The years he'd spent on Trenzalore didn't count, of course, as they were birthdays he'd rather forget anyway. Otherwise, it was always Earth: not necessarily to go down and do anything much, but just to check in on the place that had become as much home to him as anywhere besides the TARDIS could. Even though he knew how to get to Gallifrey now, there wasn't anything left of it worth looking it. He'd rather remember it as it was.
Often, in fact more often than not, the Doctor had a companion with him on his birthday. They never knew it, but he always found an excuse to run back to Earth that day if they were out on an adventure somewhere. It was nice to have company, and fun, even if they didn't know why they were celebrating, or even that they were. It was enough that they were there. Humanity's endless joy and wonder buoyed the Doctor through his darkest times, and he loved them.
This time, though, he was spending his birthday alone. The TARDIS hovered far, far above Earth; far enough away that, leaning against the doorframe, the Doctor could get a good view of the whole planet, but close enough that the dot was not pale blue, but teeming with colours and swirling clouds. He tipped his head to rest it against the frame too, gazing wistfully downward. A new year, and a new face.
Well, sort of. It was an old face— literally, the teeth might be the same, but the face itself had picked up quite a few more wrinkles, freckles, and stretches of stubble than it'd had before. He'd not taken this face down to Earth yet, and wasn't sure what he'd find there when he did. Why this face? Why now? Doctor Whoever-I'm-about-to-be— why had he tagged this old face and said, you're it? The Doctor's brows wrinkled. What was it the curator had said about revisiting old faces? He sighed, and shoved his hands into his pockets.
But before the Doctor could wander any further down this contemplative path, there was a fizzing sound from behind him, followed by a familiar voice.
"Why so glum, sweetie?"
"River!" he exclaimed as he turned, and there she was, all cheeky grin and enormous, beautiful hair. "What— how did you—"
"Spoiler," River Song winked, crossing towards him, "You should know better than to ask by now. Anyway, I couldn't let my dear husband spend his birthday alone, now could I?" She extended a hand towards him, and the Doctor finally noticed what she was holding: a large chocolate cupcake, topped with a single candle.
"River Song," the Doctor was grinning now, and his voice was warm. "You never cease to amaze me."
"That's what makes me so exciting, dearest," she quipped, and even as the Doctor reached out for the cupcake, she withdrew it, and stepped forward to drop a soft peck onto his lips. The Doctor blinked rapidly a few times.
"Well," he said when he regained his voice, "that's one way to break in a new face. That's not the poison lipstick, right?"
"On your birthday? Never." River's face changed, softening into lines of concern, and she reached up to gently hold the Doctor's face, taking in its every detail. "It's not quite the same, is it?" She said quietly, "So similar, but so different. There's so much more here now. What more have these eyes seen, my love?"
"Wait," the Doctor said suddenly, the incredibly obvious problem occurring to him, "How do you know this face? When you saw this face before—"
"Spoilers," River said again, and he found it as infuriating as ever. But it didn't matter, not really, not now, not today. The Doctor laughed softly, glancing down at the floor. "You're still cooking, aren't you? River lifted her hand away from his face, and the Doctor saw it faintly glowing with regeneration energy.
"Almost done, I think."
"Well then!" River said brightly, looping her arm through his and steering him back towards the still-open door, "We'll celebrate your birthday and your new face then! Come and split this with me."
Standing together in the entrance of the TARDIS, the Doctor and his wife ate chocolate cake, and watched the Earth turn.