I'd like to think this happened at some point. Set after "The Wedding of River Song", 11/River.
Disclaimer: I don't own Doctor Who. I dream I do sometimes, though.
She is young - so very young - when he gets the message from her. The TARDIS takes him to see her, even though he doesn't want to. Right now, he is furious at River Song. The mere mention of her name sets his blood alight and he has been keeping himself busy for the last month, trying to keep her off his mind. His death - and their wedding - have both passed, he knows, from the cheeky message on the psychic paper. He doesn't want to yell at her. He really doesn't. But he knows it's going to happen.
River is shopping on Smyslov 3 in the 43rd Century. She smiles when the sound of the TARDIS reaches her ears, but continues meandering through the shelves and aisles until she's quite finished. She pays for some of her things, hiding a few others in her pockets, and saunters off to the TARDIS, bags in hand. The ship's blue doors open on their own for her and she is delighted at this. She pokes her head in and calls, "Doctor?"
He doesn't answer. She thinks he must be somewhere, so she steps inside and carefully shuts the doors behind her. Immediately, the sound of the TARDIS's engines is heard and she is tossed about while standing next to nothing; she barely manages to keep her balance while losing two of her bags to the underside of the console. She huffs; the TARDIS liked her before, what's wrong with her now? She straightens herself up, about to speak aloud to the machine when she spies the Doctor, leaning back against the console with his arms crossed. "Hello, sweetie!" she sing-songs, placing the rest of her bags on the floor. "She took off before I was ready, half my things fell down the-" She stops, seeing the look on his face. The look that could send armies running. "Sweetie, are you okay? You look-"
"Angry," he finishes for her, jutting his chin out and working his jaw in the way he always does when he's annoyed with something. "That would be because I am angry, Miss River Song."
River is genuinely surprised, though he's definitely been angry with her before. She did try to kill him in Berlin, after all. "What are you angry for? Are my parents not with you?"
He ignores her second question; Amy and Rory are perfectly safe in their house in Earth. "I am angry at you."
"Me?" she blinks. "Oh, is this some sort of wedding night roleplay? Go on then, I love a good bit of acting-"
"No!" he shouts and she jumps in surprise. He is genuinely angry, she realizes. This isn't a game.
He squares his shoulders and marches down the steps. River stands straight to face him, face expressionless as a statue. "I don't know why you're angry with me," she snips. "So you might as well say."
He works his jaw once more, and then launches into something that she doesn't expect - a story. He tells her of an Earth shop girl, named Rose, who liked to play God. A girl who thought she could tear down the walls of two universes without any repercussions, a girl who did this terrifying act in his name. He told her to never try, but she did anyway. She was willing to sacrifice two Universes just to get back to him, despite the fact that he lived in one of those universes and would have died along with them.
"I left her," he says through gritted teeth, "because she was dangerous. I left her with a clone, under the pretense of a broken piece of myself. Because he could keep her from doing it again."
River waits a moment before she speaks. "I don't understand what this has to do with-"
"It's the same thing!" he roars, giving in to a rare burst of genuine anger. His arms flail in every direction as they try desperately to expel some of his energy. "You were willing to let this Universe burn in exchange for me. You would let billions and billions of people die-"
She bristles and shouts back, "What makes you think they wanted you to die? They didn't! None of them did! They all wanted to prevent your death! And you're obviously still here-"
"That isn't the point!" he shouts back. "I am not worth all those people, River. You were willing to kill them and take the future of every single one that never lived. I have spent my life saving them because they deserve to be saved-"
"They were more than willing to give their lives for you!"
"And that makes it okay? What makes you think I would ever want that?"
She freezes, halfway between screaming and crying. This was supposed to be a happy night. Their wedding night. Instead, the TARDIS lands somewhere of her own accord. River grabs her bags, leaving the two under the console, and marches off into the night.
One month later by his time, a week by hers, he gets another message on the psychic paper. This one is much more tame, simply requesting a visit. That's all. Nothing more. He relinquishes control of the console to his beloved Sexy. He still feels guilty for yelling at River, wishing that he could have explained it all more calmly. But he knew she wouldn't understand, and she didn't. It was hard when he was so angry.
The TARDIS lands somewhere on Earth in the 25th century. Outside, River stands waiting for him. She is calm, determined. The box materializes and she waits a moment before stepping inside. The doors shut behind her and he is standing at the top of the stairs, watching her closely.
She realizes that he was right. Though the Universe was more than happy to give itself up for him, he would never want such a thing. He spends so much time saving them that watching them burn, in his name no-less, would tear him to pieces. He genuinely loves them all.
She was raised to be his murderer, his executioner. He only married her to save the rest of the Universe, River knows that now. But her love for him is genuine too. And if she is going to earn his respect - and more importantly, his love - she is going to have to admit when she is wrong.
And this time, she is.
"You were right, Doctor," she says, before he can open his mouth to speak. "I never stopped to think about how destroying the Universe like that might affect you. And if the Universe was gone, you'd be gone too, so it doesn't really make a lot of sense." She purses her lips. She's practically a teenager, so apologies are still hard. "I'm sorry."
He deflates, both physically and emotionally. Before she quite realizes it, he's walked down the stairs and scooped her into his arms. She hugs him back, trying to keep the tears from springing unbidden to her eyes. "I'm sorry too," he murmurs into her fantastic hair. "I shouldn't have yelled. I could have handled that a lot better."
"Yes, you could," she replies, not unkindly. They both chuckle a bit, then let one another go.
"Tea?" he prompts, citing the always faithful British remedy for anything and everything.
She smiles and nods. "Tea sounds lovely." She pauses. "Mum said there's a library in here. Can I see it?"
He suddenly grins like a three year old and grabs her hand, pulling her down the TARDIS's many hallways, the tea completely forgotten.