Just a little something that popped into my head. It takes place at some point after The Wedding of River Song but before River is pardoned.
The TARDIS
The Eleventh Doctor and River were on the TARDIS, having just left their latest adventure and were now on their way back to Stormcage. But at the moment, they were arguing.
"How was it my fault we got captured?" The Doctor asked annoyed.
"As usual, you talk too much Sweetie," River shot back with a grin.
"Oh I'm sorry, who was it that started threatening people?" The Doctor shot back.
"When you get into trouble, sometimes you have to threaten people rather than make nice with them," River said pointedly and The Doctor barely resisted the urge to start banging his head against the console.
"Its times like this I miss Donna," he grumbled as he moved towards the console.
"Who's Donna?" River asked and The Doctor tensed as he realized he'd said that out loud.
"No one. She's no one," The Doctor said evasively as he began fiddling with the controls on the console.
"Well she's obviously someone. An ex of yours perhaps," River noted as she walked up beside him. "I won't get jealous if she was, so you don't need to worry about that."
"No, she wasn't an ex. She um, she used to travel with me. She was actually the last person to travel with me before I Amy," The Doctor explained, not looking at her. "Amy actually reminded me a bit of her at first."
"Really? So my mother was your Donna stand in?" River teased and The Doctor chuckled, although she noticed it was strained.
"That is not what I meant actually. They were both very stubborn, abrasive women. Donna, she was shouting at the world because she thought no one was paying attention. Her father had died not long before she began traveling with me, and her mother was in a bit of depression, so things were strained between her and Donna when she began traveling with me. Her grandfather told me once that Donna was better for having traveled with me. I'm not so sure," The Doctor said with a strained smile that didn't reach his eyes.
"Something happened with Donna?" River asked carefully.
She'd learned by now that when he was opening up, it was best to just let him talk rather than shut him down. He let these things eat away at him, if she could share the burden, she would gladly do so. But all she could do was help him as he let her.
"When Davros and the Daleks attacked Earth in 2008, I was hit by a Dalek's beam. Rather than Regenerate, I channel the Regeneration Energy into my severed hand – long story. The Dalek tried to destroy the TARDIS with Donna and the hand inside. During the processes, there was an exchange of energy between Donna and the hand. It created a duplicate of me that was half Time Lord, half human," The Doctor explained and she grinned.
"Two Doctors? I'm disappointed I messed that," she quipped and The Doctor chuckled.
"Probably best that you did," The Doctor said, shuttering at the thought of River being anywhere near Jack Harkness. "But the exchange wasn't one way. Donna was made part Time Lord; she got my mind, all the knowledge of the universe in my head."
"A human with the knowledge of a Time Lord? I didn't think that was possible," River said in surprise and The Doctor's smile became noticeably sadder.
"Because it isn't. Donna's human body couldn't handle all that knowledge, it was killing her. There was only one way to save her: I had to wipe her mind, completely, of everything to do with Time Lords. All our adventures together, the places we'd been, the people she'd met, even me. If she ever remembers, she will die," The Doctor said and a long silence descended in the TARDIS.
River stared at her husband for a long moment as he fiddled with the controls on the console, which River knew was more to have something to do than it was able piloting their next course. It was clear than what happened to Donna still haunted him, the look in his eyes said it all. But it was the way he spoke about it that broke her heart. He blamed himself, just like he always.
River placed her hands on his over the console. The Doctor looked over at her, seeing the flash Donna for a moment. Then he was left with River.
"I'm so sorry Sweetie," River said her voice filled with compassion and he smiled weakly.
"You have nothing to be sorry for," The Doctor said as he brought one of her hands to his lips, lightly kissing it. "So, in the mood for another pit stop before heading back to Stormcage?"
"And where would we go Sweetie?" River asked as she raised an eyebrow, knowing he was stalling and trying to change the subject.
"Wherever you want," The Doctor promised and River was silent as she considered.
"Well, I've always wanted to go to Asgard," River mentioned and The Doctor smiled.
"Then Asgard, here we come!" The Doctor shouted.
He put in the course and flipped the lever. River laughed as they felt the TARDIS taking off, curious to see what their next adventure would bring.
Eleven/River isn't something I've written a whole lot of up to this point, so I hope I did okay.