She'd lived with the memory of a faceless legend known as Rose Tyler haunting the TARDIS for so long that River often forgot that she was actually a real person.

Just a girl, in fact. River peered around the corner of the stall, watching a young blonde bounding along with the Doctor (gods, he was young) at her side. They looked incredibly hyperactive, somehow, as if they were so happy that they were visibly vibrating with it. Their entwined hands swung between them and laughter distributed toothy smiles across each of their faces.

River had only come here to see her, just once. And him. The two of them together. She hadn't quite expected this, no matter how the Doctor's feelings had become clear to River over time from the things he never quite said.

She'd just wanted to know what they were like together. Now she did. She wished she didn't.

The Doctor peeled off suddenly to look at something on his own, giving Rose a quick explanation and a completely ridiculous little goodbye salute. Rose merely smiled indulgently and turned in a circle on the spot, looking around her as if she'd never seen an alien marketplace in her life and wasn't quite sure where to begin. As though she was being reeled in on an invisible string, she finally made a beeline for one of the stalls. River noticed that Rose almost absent-mindedly ran her hands over the merchandise, as if her thoughts were centred elsewhere. She toyed with one of the metal trinkets in particular, while the vendor tried to convince her that the item in question was some priceless treasure.

"You'll never be caught in the rain without a hover-brella again!" the man proclaimed. "Special price of six credits for pretty girls like you."

"'Cept I haven't got any money," Rose explained, sounding wistful, and completely ignoring the inept flirtation. "Oh! But, well, my friend's just 'round here somewhere, and he's probably got plenty of – what'd you say? Credits? – so if he'd just stop muckin' about in the mechanics section already..."

Mechanics, River thought. Even though she couldn't imagine the Doctor would ever leave this girl's side for any long stretch by choice – River was all too aware that he would have spent every second of his whole life with her, if he could have – he'd still be sure to end up sorting through potential bits and pieces for the TARDIS for some time, at least.

She'd just come here to watch, but how could she let an opportunity like this pass her by?

This was monumentally stupid, she knew. River cursed silently at herself as she stepped forward. Even though he wouldn't recognise River if he saw her in passing at this point in his timeline, the Doctor had a better-than-photographic memory. He'd recognise her next time he saw her, which should be their first meeting (for him, at least). It was too big of a risk.

But then, River thought, she'd still never come across a version of the Doctor who didn't already know her. Perhaps he was supposed to meet her here for the first time after all.

"You don't want to buy that," River said loudly.

Rose turned to the side to look at River with a questioning expression.

"Sorry, you talkin' to me?" she asked.

"Yeah. You don't want to buy that," River repeated. "Bazoolium's rubbish, especially the sort you buy in a place like this. It'll break within the week."

"Hey!" the stall vendor protested. "Do I come to your work and mess around with your livelihood?"

"Oh, can it," River told him. "There're plenty of hapless tourists milling around who'll be happy to buy your junk. I've hardly sent you out of business. More's the pity."

Rose's eyes darted between the two of them and then placed the little knick-knack gingerly back on the table of goods.

She followed River out of the yelling range of the irate vendor.

"So, you seem to know your way around. I was lookin' for somethin' to give my Mum as a present," Rose said. "I keep havin' to... well, leave her. I thought it might help if I gave her somethin' to keep with her when I'm gone. Somethin' from when I was away, you know? Any suggestions?"

Gods, River thought uncomfortably. Sight-seeing gifts for the mother who was doubtless waiting anxiously back home for her daughter to arrive back safe. How was it even possible that Rose Tyler was so young?

She hadn't thought she'd see this girl and actually like her. She also hadn't thought it was possible for the Doctor to look as unabashedly happy as he had earlier, either.

Damn it.

"Do me a favour," River said suddenly, not even really sure whether she'd actively made the decision to say it or whether the words were just forcing their way out despite her. "Next time you go home to see your Mum, stay in the TARDIS. Let the Doctor handle whatever happens outside himself. Just this once, stay away from it."

"What?" Rose yelped, looking at River as if she'd burned her. "How d'you know about any of that? You been stalkin' us or somethin'?"

"I'm a time traveller," River said, giving Rose a pointed look. "How do you think I know?"

It took her a moment. River couldn't even imagine how Rose could possibly fail to recognise and be prepared for this sort of thing. Could anyone have actually managed to travel with the Doctor for more than a trip or two without having crossed multiple timelines and being forced to deal with the fallout? River found that hard to believe, given the Doctor's tendency to get into inconceivable amounts of trouble. Still, Rose did seem to reach the obvious conclusion eventually. Instead of suspicious, she now mostly just looked thoughtful.

Honestly, what had she done? River really hadn't come here for this at all. Never in a million years would she have thought she'd get it in her head to do something quite this potentially disastrous. It was the sort of mad thing the Doctor would do, if he thought the timelines might permit it.

Gods, she hoped the timelines permitted it. She'd hate to be the person that destroyed the whole universe with a few misplaced words. The Doctor was really better at that sort of thing, all told.

He was obviously rubbing off on her more than she thought. Although, then again, now she might never get the chance to pick up his bad habits. Now he might never meet her, or he might meet her and not even really notice her because he already had Rose by his side, or...

River's head hurt. She turned to retreat from the evidence of her own stupidity, the damage well and truly already done, but Rose's soft voice stopped her.

"What happens?" she asked. "What happens if I don't stay inside the TARDIS, like you said?"

River smiled bitterly, though she was facing away from Rose enough that the girl couldn't see the expression. "My life happens."

"And that's a bad thing, is it?" Rose asked, sounding perplexed.

"Depends who you ask," River replied, and walked away.

She might not even know to miss that life, if things changed. She'd just forget about that brilliant, frustrating life that she never thought she'd give up the memory of for anything, even if it meant doing something drastic just to preserve her own timelines.

But she'd seen a spark in the Doctor's so-young eyes when this girl was by his side that River knew he'd never get back once she was gone. River would be the first to admit that she had quite a few selfish bones in her body, sure. But not like that. Not to the extent that she could stand by and allow the Doctor to lose something so obviously vital to him when she could step in and do something about it.

She loved that man too damn much for her own good.

From a distance, River saw the Doctor sidle up to Rose. The girl gave him a long look, as if she was considering telling him all about her strange encounter of moments ago, but then broke into a grin and linked their arms instead. The two of them walked off chattering away, presumably off either to explore the rest of the markets or to go back to the TARDIS.

Happy. He was happy. River had to focus on that, rather than the other consequences of what she'd just done.

River had known the Doctor for so long that she didn't know what her life would be like if he wasn't ever a part of it. But then, she had a pretty good idea now what he'd be like, and she wanted that for him.

That had to be enough for her. She couldn't regret it now.

She tried not to think about the fact that the Doctor would likely never even know what River had just potentially given up for him.

~FIN~