A/N: So I've never written for DW before, and I'm generally intimidated by writing for big fandoms... but Eleven and Clara kind of stole my heart after the Christmas special, and I had to do something.
"Perhaps the universe makes bargains after all."
The Doctor knew the universe didn't make bargains. It had never stopped him from trying, of course; gods knew he'd tried, pleaded time and time again for lives and loves, for do-overs and timelines that could never be. Clara was hardly the first. "I don't think the universe makes bargains," Madame Vastra had spat at him in the TARDIS, and even as he argued back he knew in his hearts she was right. He knew that Clara was dying and he couldn't stop it and it was his fault because he should've been thinking more clearly, should've shut the TARDIS door, should've stayed closer to her.
Should've, should've, should've. His entire existence was a series of those.
He'd saved the world, and she'd died anyway. So much for bargains.
But then he'd seen her gravestone and realized the impossible. They'd met before, in another time, another place, thousands of light-years away. Oswin Oswald. Clara Oswin Oswald. Junior entertainment manager. Barmaid and governess. And if there were two, maybe there was a third.
Perhaps it wasn't a bargain. It definitely wasn't a miracle. But it was something, and he'd take it for now.
The TARDIS had traced another Clara to London, 2013. He'd knocked on the door to her flat and she'd answered, this girl with his Clara's face and voice, staring up at him with the curious expression he so associated with her.
"Clara Oswin Oswald," he'd begun, holding up a key and secretly enjoying the flicker of confusion that crossed her face, "would you like to see the stars?"
The Doctor knows the universe doesn't make bargains. It doesn't give out rewards for good behavior, for saving peoples and planets and not backing down in the face of everything that has ever been thrown at him. Whatever impossible thing Clara is, she isn't a miracle or a reprieve. Her existence isn't some cosmic blessing; knowing how things in his life go, it'll likely be just the opposite. Living twice had been pushing it. Living three times is taking the limits of the universe to their absolute maximum. Clara's on borrowed time twice over, and perfectly human on top of it, as far as his scans can determine. And he knows what happens to humans, in the end.
She's a mystery to him, in a different way than humans usually are, and he's dying to solve her but terrified to at the same time. The mysteries that find him never end well, and he's had about enough of endings for a while, thanks very much.
All he wants is to show her the stars.
So he does. And he keeps her as safe as he can (she's the worst one yet, with a curiosity to match his own, and he can hardly even blink without losing track of her), because he'll be damned if he's going to be careless with her again, and there's no guarantee there's more Claras out there. Even if there are, they wouldn't be this Clara, and he's grown rather fond of her: of the faint smell of burned soufflés that now permeates the TARDIS, of the way she leans in close and watches him intently whenever he's flying even though he knows she can't possibly understand (after all, even he's not always sure what he's doing). It doesn't mean she stays out of danger; like everyone else he's ever taken along with him, danger seems to find her. It does mean that sometimes he finds his hand on the back of her neck or his arm looped through hers and can't quite remember how or when it got there, and it also means that sometimes he goes to slightly extreme lengths to keep her out of harm's way.
They fight about it, once. Not the playful bickering Clara seems to so enjoy, but a proper row, after he tricks her into the TARDIS and locks her in on a particularly dangerous planet. By the time he makes it back, singed and dirty but otherwise unhurt, she's had a few hours to stew and she lets him have it as soon as he walks through the doors.
"What the hell," she begins, marching up to him with her hands on her hips, and he's not sure he's ever seen quite so much fury in such a small package, "did you think you were doing?"
He steps around her, ignoring the finger she's thrust accusingly in his face, and heads for the TARDIS console. "Keeping you safe," he says tersely, fiddling with a knob that he's (pretty) sure has no actual use.
"You asked me if I wanted to see the stars, remember?" She follows him to the console, and he can feel her staring him down but he doesn't look at her. "You turned up on my doorstep and handed me a key and I came away with you. And sorry, but I was expecting a bit more adventure and a bit less coddling!"
"I'm not coddling you, Clara-"
"I may not be a thousand-year-old timelord but I am an adult woman and I can take care of myself-"
"Like you did on Onzod?" he interrupts as he flicks a switch on and off (or off and on, or on and more on; he really shouldn't have thrown the manual into that supernova).
"Oh, sure, get thrown into a Kwian prison camp one time and suddenly sweet little Clara needs to be led around by the hand and locked in the TARDIS because she's too stupid to-"
"I don't think you're stupid, I just-"
"-think I'm a child? Think I can't keep up with you? What, Doctor?"
"I just am not going to watch you die again!" he roars finally, whirling to face her, and there's a flicker of what he thinks is recognition across her face before it's replaced with confusion.
In the end, he makes her a deal, there by the TARDIS console, with his arms wrapped around her and his chin resting on her head (she makes a crack about how bony it is, and he smiles). He'll be less overbearing if she'll promise to just listen to him once in a while. When he lets go, she makes a "cross my heart" gesture and winks at him before skipping off, presumably to burn another soufflé, and he realizes that impossible Clara doesn't make bargains either, that she's going to drop this one as soon as it's convenient for her to do so.
Of course, if she doesn't stick to her end of the deal, he's going to have to fight her on it.
And when the universe decides to renege on their bargain, he'll fight that too.
Until then, they'll run.