The long, spoken bit at the very end is the last thing said before the old series of Doctor Who went off the air years ago. I found it appropriate.
Disclaimer: I don't own Doctor Who. If I did, this would absolutely happen.
He watches her in disbelief. How is she here? More importantly, why? Amy and Rory stand behind them, holding each other in confusion, backs against the TARDIS. The woman before them is unfamiliar to them, middle-aged and ginger of all things. She has a hand to her chest under the red light of the sunset, breath heaving, and the Doctor, between the woman and the TARDIS, can't move an inch. She cannot be here, never mind that they are in Chiswick. He stares as her eyes glow a beautiful gold. They lock onto him and she smiles gently. Happily.
He has missed that smile. That beautiful smile, so full of compassion and grace. He watches the golden light in her eyes change ever so subtly and he quickly jumps back. He knows, as impossible as it is, what is about to happen. Amy and Rory's voices are but echoes behind him.
But it makes sense.
His mind flies back, back to so long ago when he stood at her side in the great expanse of the Library. He had saved over four thousand people and her, his River, one he could not bear to let die... Because she was special.
"This is her diary... What do you think? Shall we peek at the end?"
She knows how to drive the TARDIS. A brief flash of the human Doctor flits across his mind as he watches the scene in front of him. So confused and yet filled with true joy, a feeling that he has not felt in years.
"I was taught by the best... Too bad you were busy that day."
They were always mistaken for a couple. No matter where they went, always a couple. A clue from the universe, one that he had been too blind to see. The bright light erupts from her skin and she is standing there, head thrown back and screaming because it hurts.
"Oh, no no no no, we're not – we're not married." "We're so not married." "Never." "Never ever."
Amy should have been the only person to remember him after the Big Bang Two. But River did. She gave Amy the blank book, a reminder of the gaping hole in the universe that he had left behind. The Artron energy flies in every direction and he pushes Amy and Rory behind him protectively as they walk forward to see.
"The writing's all back, but I didn't peak." "Thank you." "...Who are you, River?"
She knows Old High Gallifreyan. The home box from the Byzantium had Gallifreyan symbols. The oldest cliff face in the universe, defaced with his home language because he would not pick up his phone.
"I thought we could try the planet Felspoon... Mountains that move. Can you imagine?" "And how do you know that?" "Because it's in your head! And if it's in your head, it's in mine!"
She knows his name. He sees her features change before his eyes. Red melts to gold. Blue to effervescence. Beauty to beauty. The energy disappears as quickly as it came and she is standing there, with hair that is no longer ginger and a face just as familiar as the one she left behind.
"That was a two-way biological meta-crisis. Half Doctor... half Donna!"
Wisps of time whispers things to him, things he could otherwise not know. A Dalek begging for mercy. Her unique timeline. Jack's blaster. She is Donna Noble... and you were so, so sorry. So sorry because you somehow understood her pain...
The woman collapses to the ground, the Doctor barely bending in time to catch her. Dozens of questions fly from Amy and Rory's mouths, but he does not answer a single one. He gathers her in his arms and promptly enters the TARDIS, taking her to the room that is, was, and will always be hers. She is unconscious for the time being. He gently sets her down on the mattress and asks Amy and Rory to leave, promising explanations. They reluctantly exit and shut the door behind them. He pulls a chair to the bed and sits.
He is careful; probing the mind of an unconscious life form is dangerous, but he knows what he is doing. He gently places a hand on each side of her face, scanning her memories. His suspicions are proven correct; a human regeneration, at least in her case, wiped all of her previous memories away. He concedes that it makes sense; humans are not meant to regenerate and he notes that not everything is perfect. Her brain did what it had to, the only thing it could do, in order to cope with the Time Lord mind. The Time Lord consciousness had been incorporated into her new psyche; certain things have been omitted, certain things have been kept. She is no longer the hot-headed ginger, but the gun-toting blond. He gently touches her forehead. It is cool. No sign of fever. He closes his eyes and lets out the breath he did not know he was holding.
When he opens his eyes again, she is looking back at him. He inhales sharply. She blinks calmly, unafraid. "Where am I?" she asks, voice soft and musical.
"In my TARDIS," he explains, awkwardly taking his hand back and folding it in his lap.
"Ah," she says and that's all the explanation she needs. She takes in the room with interest. "This room feels strangely familiar."
"Ah, well... Do you like it?" It seems odd, to see her in this room that is and yet never was hers.
"I do," she confirms, slowly sitting up in the comfortable bed. She wants to say something and it sounds strange to her, but she speaks anyway. "I confess I don't really know who I am."
"That's alright," he soothes. "You're... brand new."
She eyes him, but says nothing. "Do you know who I am?"
"I do," he says, an echo of her own words. "You are a traveler."
"Am I?" she asks, rolling the word on her tongue. "A traveler. Traveling... Sounds like fun."
His green eyes sparkle and she cannot help but stare into them. "It is," he insists, standing from the chair and replacing it. "Do you have a name?"
"I thought you said you knew me," she said cheekily.
"I do," he said. "But did it ever occur to you that, perhaps, I don't know your name?"
"It's..." She pauses. It occurs to her that she does not have a name. A moment passes, then another. The man in the bow tie watches her carefully. Finally, her lips part. "My name is River. River Song. And yours?"
"The Doctor," he answers and she does not find this name peculiar in the least. "River Song, hm? What an interesting name." He claps his hands loudly and rubs them together. "Well, River Song the traveler, what now?"
To his astonishment, she knows precisely what to do. She reaches for him and says, "There are worlds out there where the sky is burning, and the sea's asleep, and the rivers dream. People made of smoke and cities made of song. Somewhere there's danger, somewhere there's injustice, and somewhere else the tea's getting cold. Come on, Doctor — we've got work to do."
He smiles brightly and takes her hand.