A/N: An individual's 'negative face' is their desire to remain autonomous, to be unimpeded in their actions. So, you can threaten their negative face by asking them to perform a task that they might not otherwise chose to do (e.g. to help you move apartments or loan you their rake). Positive face is a person's desire to be well regarded by those around them (so you threaten it by insulting them or otherwise doing something that might lead to their reputation taking a hit). We mitigate face threatening acts using various politeness strategies.

:)

Chapter 11: A Threat to Negative Face

Rose was distracted. Oh, she wanted to pay attention to the words actually leaving the Doctor's mouth, it was a gift she had not anticipated after all, but she found her attention drifting. It was just... Of course, she'd heard him speak before. They'd had one stilted conversation in the TARDIS just after he changed and another that ended in his collapse after the... tree... incident. But, well, he had spent both of those brief interactions in pain or afraid or worried about her reaction. Then, he couldn't talk to her at all and suddenly all their conversations were stilted and slow. She'd seen how frustrated he was by the dam up in his mind, the slow release of words in a language no one but him spoke.

Now though? He was animated, grinning and serious all at once, displaying the sort of determination she'd seen flashes of since his changed. He looked healthy and cheerful, despite the terrible problem he was trying to solve and she should be happy. She knew it. She knew she should be ecstatic because he wasn't hurting anymore and they might go back to how they'd been.

Except.

Well, there was no going back was there? Her Doctor, the Doctor who'd held out his hand and shown her the end of her world before taking her for chips, he was gone and Rose hadn't realized until just now what exactly that meant.

No more big ears or goofy smiles, no more smell of leather or blue eyes crinkled with a grin he seemed almost ashamed of allowing. No more northern burr to his vowels.

Now she had a gangly stranger with a shock of fluffy hair and a smile that curled at the corners. He was still right fit, just in a very different way than he had been. Plimsolls instead of boots.

Her heart twisted in her chest because she wanted to be happy and she wanted to be sad and she couldn't bring herself to be fully either thing.

So, Rose sat on the hard grating on the TARDIS console room and watched as her new Doctor first listened to Belinda-9's explanation of the Scan and then exploded into nervous motion. He couldn't seem to stop moving these days, like his brain only worked at the same pace as his feet. During their lessons this last week, he'd constantly been popping up from the floor or the sofa or whatever vaguely horizontal surface he'd last thrown himself upon to gesture and demonstrate and generally faff about while she tried to remember how verbs worked.

"Right," he said, "So, your engineers try to solve disease. Which, first of all, that's a bad idea. Oh, I'm sure it came from a good place, the worst ideas always do, but really how did you think it was going to turn out? That you'd just get rid of all germs and then... what? No one would ever visit your planet again and you'd be suddenly safe from one of the few universal constants? Please."

Belinda-9 had her arms folded across her vast chest. "It as not my plan," she rumbled. Rose wondered in the Doctor had always been so incapable of sensing when he was toeing a dangerous line in conversation. It was obvious that the other woman was bordering on insulted and yet... The Doctor kept talking.

He flapped one hand at her, "Of course it wasn't, Rose wouldn't be friends with anyone that dumb. Well, except Ricky but we all make exceptions."

And then he did something she'd never seen him do before.

He said something rude, then turned to look at her, a little smile on his face and his eyes wide. It was, Rose realized with a desperate desire to groan, a joke. He'd made jokes before (obviously) but of a very different sort. Now, he was looking at her and inviting her to laugh with him or scold him or react in some way.

She settled on scowling. He knew her feelings about how rude he was to Mickey, a scowl instead of a laugh wouldn't lead to suspicion. Wouldn't lead to the sorts of questions she wasn't sure she had answers for right now. Except, well, she'd made a rather critical oversight. Because, in all her thoughts on how he'd changed, she'd forgotten something very important- he was not just the Doctor, he was her Doctor and he knew her better than anyone else in the universe at this point.

So, instead of accepting her scowl and moving on, his manic energy puttered to a halt. He looked at her much more seriously, leaning forward slightly.

"Are you alright, Rose?" he asked. He still drew out the vowel of her name, she realized, still savored it the same way he had when speaking Gallifreyan.

Rose tried to smile at him. She was happy, she really was.

She was.

His own grin had entirely faded now. His hands, which had been gesturing wildly as he spoke, fell to his sides. He looked between Rose and Belinda-9 before seeming to come to a decision.

"Is it safe for you to go back to the tunnels?" he asked Belinda-9.

Belinda-9 looked between the two of them. She had a complicated look on her face that Rose did not understand.

"Rose," she said as quietly as she could manage. Even still, her voice could only be classified as a rumble. "Could I-?" She gestured towards the door, away from the Doctor. Rose pulled herself to her feet with her good hand, realizing once more how very uncomfortable her broken arm had become.

She shot the Doctor a reassuring look as she crossed the space to stand beside Belinda-9. She trusted the other woman and knew that she wasn't a danger, but the Doctor had only just met her and tended to be over protective, even in less fraught times.

"Yeah?" Rose asked when she was close enough to speak quietly and be heard over the background noise of the TARDIS.

"Are you," Belinda-9 hesitated, glancing over to the Doctor. Rose followed her gaze and had to suppress the urge to smile. He was acting deeply engrossed in something on the viewscreen, a little furrow between his brows and a downward tilt to his lips. It might have been a convincing act if his eyes didn't keep drifting towards the women before darting back to the viewscreen. In fact, Rose would have been willing to bet almost anything that what he was actually doing was trying very, very hard to eavesdrop without appearing to do so.

"Are you safe with this man?" Belinda-9 asked. Rose blinked. That- that was not what she had expected to hear at all. Belinda-9 saw her pause and continue, "I have not known you long little one, but you arrived to me with a broken limb and your... companion does not seem very stable." Her gravel-against-metal voice was low, a rumbling half-growl that Rose suddenly discovered made her feel incredibly fond.

Out of the corner of her eye, Rose could see the Doctor grow very still, losing all pretense of not listening to them.

"There's no safer place in the universe," Rose said and she knew it was true. Sure, they frequently stumbled into trouble and had to run for their lives more days than not, but she also knew, without a shadow of doubt or hesitation, that the Doctor would move the literal stars to help her if she needed it.

Belinda-9 studied her for another few seconds before nodding. "If you're sure," she said, "You don't have long before the next Scan, I'll keep the tunnel open for you as long as I can."

Overwhelmed by gratitude for the huge woman, Rose surged forward and wrapped her arms as far around her as she could. Belinda-9 was a furnace, solid and warm and incredibly reassuring to press her face against. Massive hands covered her back, holding her close and secure and suddenly Rose was fighting back a few traitorous tears. So much had happened, had changed, in the last week and Rose realized how very badly she wanted to hug her mum.

Emotions were odd things, the Doctor often thought, little surges of chemicals and interactions that flooded one's body with molecules that manipulated thoughts and the ways the world might be perceived. At different times he loved them and hated them, and even those views were themselves dictated by chemistry.

Just now, he was trying to fight back a veritable flood of complex organic molecules that wanted to tug him into feeling things he was sure would be overwhelming at best and debilitating at worst. He should have anticipated that using the Chameleon Arch in the way he had would have an effect on the delicate balance of his internal chemistry, tilting him from equilibrium towards chaos.

Adrenaline swept across him, heightening every other feeling and the corners of his eyes pricked as he watched Belinda-9 embrace Rose. The human leaned into the Gullinets' chest, her slim form almost entirely engulfed by the reptiliform. He felt shaky and odd, thrown from the rockers of logical thought by the implication that he had hurt Rose, that he even seemed like the sort of person who would hurt- He was not offended or hurt. Rather, he realized he was feeling guilty. Rose was hurt and clearly feeling a bit overwrought, her own chemical cocktail driving her to seek comfort from the closest maternal figure available. He caught the faint scent of salt and realized she was crying.

That's it. They were going to find the nicest, safest, most boring beach planet out there and spend a solid week laying in the sand and getting a tan and then he was going to take her to see the diamond cliffs of Hureshiin and they would watch the sunset refract through the crystals into a riot of rainbows and then he would apologize for everything in the last two weeks.

(Briefly, the thought of finding Jack and dragging him along occurred, but the same something that rebelled and ached at the Bad Wolf's effect on the other man screamed out and he knew he wasn't ready for that yet. It didn't matter, he told himself, he had a time machine, he could go back to the moment they left Jack and it would all be okay. He just needed a little more time to get used to a living Fixed Point.)

Eventually, Belinda-9 pat Rose one final time on the back and pulled away. The Doctor watched as Rose sniffed and scrubbed away the evidence of her tears. The chemicals betrayed him again and suddenly all he could think about was kissing the salt from her cheeks, pressing his forehead to hers and holding her until she smiled and laughed and-

"Remember," Belinda-9 said loudly to include him in the conversation. He forced himself away from those impossible thoughts, "You only have a short time, don't wait about."

The Doctor nodded. No, they would follow in only a few minutes, he had no desire to put either Rose or the TARDIS at risk.

"A few minutes and then we're in the caves," he assured her, "Just need a quick convo with Rose."

Belinda-9 gave him one more measuring look and he found himself wondering if she was related to the children he'd met before. They had the same sort of even, judgmental quality about their expressions. Then, she hefted the bags of food into her arms and was gone.

Rose watched her leave, turned half away from him with her arms wrapped around her stomach. An awkward silence descended upon them.

"Ah, I, uh," he rubbed one hand down the back of his neck. His gaze snagged on the cast, "Come on, let's get that fixed up before we go back out there."

Rose jerked, as if startled by his speech and he winced. Of course understanding him was going to be a bit of a shock and here he'd been, babbling away like normal. Even now the desire to speak was pressing against his throat, words clamoring to escape and fill the silence. He had a feeling the mouth on this iteration of himself was going to be the stuff of legend.

She looked down at her arm. "Sure," she said, "Yeah, okay."

He stood very still as she crossed the space between the door and the hallway that would lead to the infirmary. He didn't know where this hesitation was coming from, he'd been perfectly comfortable curled up in the loveseat in the library not three days ago. Why was he now so unsure about moving closer? His entire body burned with the memory of their embrace when he'd entered the TARDIS.

"Doctor?" Rose asked, "Are you coming?"

He jerked himself from his runaway thoughts to hurry to her side. She grinned up at him as he approached and something in his chest settled just a bit. She'd been so quiet since the revelation that he could speak something other than Gallifreyan again, he was- well, he was realizing now that he'd been worried.

"So," Rose said, wrapping her good arm around his, "What did you get up to while I was making friends?" She still sounded a bit hesitant, a bit unsure, but she was smiling and she was touching him and that would always be enough.

"Oh, you know," he said with a smile, "This and that. Made some friends of my own, ate some fruit, met the locals."

"And they didn't try to kill you? I'm impressed." There it was, there was that cheeky smile he so adored. His hearts thumped in tandem and he had to swallow away the nebulous emotion that tried to overcome him.

"I'll have you know I'm very well liked in most places," he said archly, "People love me."

They entered the infirmary.

"Really? Why haven't we ever visited a place where they like you then?"

He helped her up onto the exam table and turned away to pick up the osteogenerator.

"Maybe it's you," he mused, "I've never been in as much trouble as I have since you joined me. Maybe they don't like you."

She stuck her tongue out at him and oh- that really was unfair wasn't it? She had no right to make him feel so irrepressibly fond, so deeply, madly, irrevocably in- Well, to make him feel the way she did at such a childish gesture.

He crinkled his nose at her in retaliation and suddenly they were laughing. The odd tension in the air vanished.

"Let's take care of that," he said when he managed to breathe normally again. He was still smiling and, he realized with mild shock, he had no desire to ever stop. Smiles had felt so rare and precious before and now, well, Rose was looking down at him and holding out her arm and he couldn't imagine not smiling.

He flicked the switch on the little device, slowly running it across the outside of the ragged split. Rose giggled again.

"Tickles," she said, "Oh that's so weird."

He snorted, "Humans. I use a bit of technology your people won't invent for nearly a thousand years and all you can say is it tickles."

She nudged his ribcage with the toe of her shoe. "Rude," she said. He shrugged. It might be rude, but it was true and she didn't look mad.

They subsided into a much more comfortable silence than before.

"How are we going to help them?" Rose asked after a few minutes and he delighted in the plural pronoun.

"Well," he said, drawing out the word, "I think it really should be a simple fix. Or a simple not-fix."

"What does that mean?"

He paused to focus the osteogenerator on the worst portion of the break then spoke slowly, trying to explain his idea without sounding condescending or rude.

"They're idea was rotten from the start," he said, "You can't just decide to get rid of all the bacteria on an entire planet. That's not, that's not the way nature works. Even if the Scan hadn't gone wrong they would have had a total ecological collapse." He looked up. Rose was watching the small movements of the osteogenerator with a tiny line of concentration between her brows. "At the most basic level, the soil needs bacteria to break down dead roots into nutrients and without that nothing would ever grow. They'd have starved even if it worked as it was meant to."

"But, what about the diseases? Couldn't they have just picked which germs to get rid of and which to keep?"

He shook his head.

"Not at this scale. You can do that sort of thing for a single person, maybe a single room, but not an entire planet."

"That's why the version of the Scan in the entry shaft worked?"

He nodded, though this was the first he had heard of anything like that. There was no reason why a small scale version of the technology shouldn't work.

"Yes," he said, "So, really there is no fixing it. All we can do is destroy it and make sure they never build anything like it again."

Rose sighed. "That makes sense," she said, "But I still don't like it. All they wanted was to not get sick. I hate that Belinda-9 lost her partner because of something that was meant to be good."

He thought of the way the children had watched him eat his slice of fruit, their eyes huge and shining. He swallowed back the guilt.

"Yeah," he agreed.

The osteogenerator beeped in indication that its job was complete. He set it aside and picked up a small pair of scissors to cut away the bandages.

"The only problem is knowing where the main interface is located," he said, "They've lost so much, so many people. I'm not sure there's anyone who still remembers."

"Belinda-9 might?" Rose suggested, "She was telling me about her partner, Terry-K3. She said he was an engineer and that he'd worked on a lot of big projects. Maybe he worked on something to do with the scan? She'd have known where he was going to be working, right?"

He grinned up at her even as he kept slowly unwrapping the bandaged.

"Rose Tyler, you are an utter gift," he said.

"Why?"

"Because, I can do us one better than asking Belinda-9 if she remembers."

"Oh yeah?"

He nodded, "When I was trying to get into the shaft where you fell, I ran into a child who dragged me to the caves just in time to avoid, well, you know."

He shuddered at the memory of the other Gullinets' faces as the Scan unspooled their atoms and unwrote them.

"Yeah," Rose whispered. She pressed her foot forward again, pressing it to the side of his ribcage much more gently than she had before. He had to resist the urge to lean into the touch.

"Anyway, I followed them and found a small group of other Gullinets. They gave me a little fruit and introduced themselves and here's the kicker, there's a man there named-"

"Terry-K3!" Rose had jerked upright. She pulled her arm free from him and was yanking at the last of the bandages, "We have to go! Belinda-9 is so sad- we have to let her know he's alive!"

He reached out and took her arm back, smoothing his fingers over the revealed skin. He told himself he was checking for any remaining contusions, but in reality he just needed the reassurance that she was once more whole and healthy. She allowed the gentle touch for a few seconds before she grasped his hands with her other one, stilling their movement, her fingers were hot against his.

He looked up at her. She was seated at the very edge of the exam table, leaned slightly forward. Her hair had begun to escape the loose tie she'd tried to use to contain it, she had a smudge of dirt across her nose and her lower lip was cracked. He swallowed.

"Doctor?" she asked. Her eyes burned into his. Once more he could feel his hearts pounding away.

Her left index finger twitched against his hand.

In later years he would never remember who moved first.

In the end it did not matter.

The concept of a catalyst originated in chemistry. See, if you took a supersaturated solution, a concoction pushed past it's natural limits through extraordinary means, heat and pressure and forcing elements together which may never have met- you take that solution and you add one thing, one little drop or chip or particle and suddenly the solution changes.

Precipitate.

Rapid crystallization.

Two individuals surged forward to meet in the middle, desperation and worry and fondness and fear and no small measure of love precipitated out and away until all that remained was hands on faces and lips on lips and breath shared between two sets of lungs.