The Doctor was at a party when he saw Rose Tyler again. The music was loud and raucous, and he was having a great time. Suddenly, there came a flash, like that of a strobe light, and there she was, stumbling in the door. Her arrival went largely unnoticed, and the party continued unabated, but in the center of the room, the Doctor stopped dead. He felt a little kick in the back of his mind. Unconsciously, he glanced over at the mirror hanging on the far wall. There was the bow tie, the tweed, the peculiar face and the mop of hair. Slowly, he blinked, and with his eyes closed saw the image change, the curves of the face becoming angular, the hair rising partway off the head, the whole body lengthening, growing taller, more assured, losing its awkward stance. A normal tie. Pinstripes. By the time he opened his eyes, the change was complete. The body was still that of the Eleventh Doctor, but the consciousness inside was that of the Tenth.

Slowly, the Doctor crossed the room to where Rose was standing, and took her hand. With a gasp, she looked up. For a moment it looked as though she was about to hug him, then the light in her eyes died, and she looked away.

"Sorry," she said. "For a moment I thought... The way you took my hand, it felt like someone I lost, someone I've been looking for for a very long time."

"Oh, Rose Tyler," the Doctor said, swelling with pride. He leant over, and whispered in her ear. "Run!"

And then she was hugging him, properly, and he was hugging her back, crushing her to him, and all the feelings that had died away with his regeneration roared back into being, all his love for her, all the pain he'd felt at losing her.

Minutes passed, and suddenly the Doctor realized that Rose had grown still in his arms, that she was crying.

"Rose, what is it?" he asked frantically.

She glanced up. "I'm sorry," she whispered, then buried her face in his chest again. Gently, he cupped her chin, tilting her head up so he could look her in the eyes. Finally, she spoke again.

"I promised you forever, Doctor. I promised, and I let you down. I dunno, maybe, maybe I don't get back to you, maybe I do, and we travel, and I die, I dunno, but whatever, you had to lose me, and I'm so, so sorry."

"Look, Rose," the Doctor said, firmly, "this is me. You've found me. It all going to be okay."

But she was shaking her head.

"I can't stop though, can I?" she said, and her voice was steady once again. "I've got to keep going. This is too late. I've got to keep going back, find younger you, save the world."

She smoothed the lapels of his coat, and a grim, jealous image of the Metacrisis Doctor shot through his she was stepping back, away, pulling a small disc from her pocket.

She turned to look at him, and smiled at his tears, even as matching ones rolled down her cheeks.

"I wouldn't have missed it for the world," she breathed.

And then she was gone.