Title: Under the Weather
By: _usakeh_
Fandom: Doctor Who
Pairing: Jack/Nine
Rating: PG
Author's Note: This was written for taffimai, who also was kind enough to provide me with the title for this rather cracked-out little tale. And kudos to anybody who can, like taffimai, pick up on the super geeky math references made in the story. With that, enjoy!

“Jack? Jack," the Doctor exclaimed, peering down beneath the TARDIS's main console. "You said that you knew what you were doing."

"I do," Jack muttered. His voice sounded oddly muffled. "I know exactly what I'm doing. I always do."

"Mind telling me how sleeping there is going to get the TARDIS working again, then?" The Doctor raised an eyebrow inquisitively. At first, Jack didn't respond; when he finally did, his voice sounded fainter still.

"The TARDIS just needs to...spend a little time with me. Up close and personal," he added cheekily, "if you know what I mean."

"I don't think I want to know." The Doctor sighed. "Just get it working again. Understood?"

"Yes, sir." There was a long pause; then, to the Doctor's surprise, Jack dragged himself out from beneath the console. "There's just...well, I'm having a...difficulty, of sorts," the man managed at last. He looked flushed, the Doctor noted. Now that was strange. He'd shown no evidence of having any shame whatsoever thus far; why would he start feeling embarrassed about anything now?

"A difficulty?" The Doctor stared down at Jack, who had yet to get to his feet. That was odd, too. Could something really be the matter with him? "I warned you about going to that party," he said at last, shaking his head. "I saw the drinks they were serving. They were not meant for human consumption.”

"I've had ‘em before.” Jack coughed. Then, grimacing, he added, “Loads of time, in fact.”

"Is that so?"

"You bet." Jack nodded. Then, suddenly, he placed his hand on his forehead and groaned aloud. "Damn."

"Sure those drinks didn’t do you any harm?"

"Yeah." Jack closed his eyes, and the Doctor squatted down beside him. Beneath his greatcoat, the man was shivering.

"So: are you going to tell me what's wrong, or are you just going to lie there looking miserable?"

"At this point?" Jack opened his eyes again. "I think I'll lie here looking miserable, thanks. I just…" Jack’s voice trailed off mid-sentence, and his eyes glazed over. The Doctor snapped his fingers twice in an attempt to get him to refocus; when Jack didn’t respond, he shook the other man as gently as he could.

"Come on, now, Jack. Tell me what’s wrong. I am a doctor, you know."

"You are?" Jack's voice was rough, and he was speaking so softly the Doctor could bearly hear him. "Right. You are."

"Your head aches. Your throat hurts. You've probably yourself quite a fever there, too." The Doctor reached out and gently touched Jack's forehead. "Did you dance with anybody last night?”

"Dance with anybody?” Jack echoed. He looked genuinely perplexed. "No. No, that doesn’t…that doesn’t make sense. Couldn’t have gotten sick from one of them.” He paused to catch his breath, and the Doctor felt real anxiety ripple through him. “Couldn’t,” Jack repeated. “I was the only human at that damn party. Just Riemanns and Wronskians." He shuddered.

"Precisely." The Doctor took a deep breath. "Did you dance with any of them?" Then he raised his hand, cutting Jack off before he began. "No. Silly question. Of course you did. And that's how you caught this. Wronskians carry small parasites in their skin. Did you know that?" Jack placed his hands on his stomach, and the Doctor quickly grabbed a bucket from the area in which Jack had been working. He was probably going to need it.

“Not…not so much, no,” Jack managed at last.

"Didn’t think so. And you probably didn't know that the parasites like humans even more than they like their usual hosts, did you?" Jack groaned and bent over; just in time, the Doctor handed him the bucket. When Jack finally got his churning stomach back under control, the Doctor removed the bucket and helped him sit up again. “Better?”

“No,” Jack replied sullenly.

“Hey,” the Doctor protested. “Don’t give me that look. It’s your own fault!”

“How is it my own fault?” Jack croaked. “My dance partner gave me parasites. Alien parasites.” For a second, Jack looked so despondent the Doctor couldn't help but feel at least a little sympathy for him despite the fact that he had utterly and completely brought it on himself. "Alien parasites,” Jack repeated. “I've been given better gifts from my dancing partners, that's for sure.”

"Have you now?"

"Yeah," Jack said, voice heavy with exhaustion. After a long pause, he added, "Okay. I understand now. I got infected with alien parasites. What am I supposed to do about it, doctor?"

"Nothing."

"Nothing?" Jack started to slide back down against the floor, but the Doctor caught him and held him close. The man was heavy. "What do you mean, nothing?"

"If you're lucky, your body will be able to burn them out on its own. Humans have a higher body temperature than Wronskians do, and with that fever you're running...most likely, after being sick as a dog for a few days, you’ll be just fine.”

"What if I'm not lucky?"

"Try not to think about that possibility right now," the Doctor instructed.

"Okay." Uh-oh. Jack really had to be feeling awful, the Doctor thought, if he'd accepted one of his statements without arguing at all. He had to get him lying down, and fast.

"Jack?"

"Huh?"

"Can you get up?" The Doctor held out his hand. "I'll help you. You need to get to bed."

"If you put it that way," Jack muttered, raising an eyebrow, "I'll give it a shot."

"Ready, then?" Jack held out his hands; the Doctor clasped them in his and pulled until Jack staggered to his feet. "Good. Good job. Now walk with me."

"Walk with..." Jack's voice faded; for a second, the Doctor feared that the man was going to faint. But he recovered. Soon enough, he was complaining again. "Some doctor you are, not being able to cure this."

"Fancy walking to your room on your own?" The Doctor asked. Jack only leaned against him more heavily in response. "Thought so. Then quit whining. You're the one who danced with the Wronskians. I did warn you, did I not?"

"You didn’t say anything about alien parasites."

"Are you sure about that? Maybe you just didn’t pay enough attention." The Doctor dragged Jack around a corner and, at long last, swung open the door to one of millions of rooms hidden away within his ship. "You'll pay more attention next time, I bet."

"Uh...yeah." Jack flopped down on the bed the second the Doctor loosened his grip on him. The Doctor quickly rolled him to the side and covered him with blankets. Then he placed his hand on Jack's forehead once more. "Hey," Jack protested. "That's cold."

"Sorry." The Doctor took a deep breath. "Do you need anything?"

"Heavy duty drugs? A dozen hypervodkas?"

"I don't think those would do you much good. I'll bring you a glass of water," the Doctor said, taking a step towards the door.

"Wait!" Jack tried to sit up and failed miserably. "Don't go! You seriously can't do anything about this? Not anything?"

"Nope." The Doctor shook his head. "The fever's got to burn the parasites out. Sorry. I bet you'll think twice before dancing with another Wronskian, though."

"You can say that again," Jack groaned. “Not worth it. Didn’t even…damn, it’s cold. Don’t think…I’ve ever…been quite…this cold,” he continued, shuddering even beneath the blankets. “I don’t think…I’ll ever…be warm again.”

“You will be, Jack,” the Doctor reassured his patient, sitting down on the edge of the bed. “Just not for a while.”

“Hey! TARDIS!” All of a sudden, Jack’s voice was surprisingly loud. “IT’S TOO COLD IN HERE. TURN UP THE HEAT.” As soon as he stopped shouting, Jack began gasping for air. He pressed a hand to his chest and glanced at the Doctor in alarm.

“You can either shout, or you can breathe properly.” The Doctor placed his hand over Jack’s. “Can’t do both right now.”

“IT’S…TOO…COLD,” Jack managed, and promptly began hyperventilating.

“You’re only hurting yourself, Jack.” The Doctor spoke slowly, calmly. “And my ears. Please don’t do that again.” Jack reached out, frantically, towards him. “Yes, I know you can’t breathe properly now. I warned you, didn’t I? But it will pass. Just stay calm. Stay calm, Jack,” he repeated, clasping Jack’s outstretched hand in his. “It’ll get better on its own.”

“On its…own?” Jack’s voice, once again, was barely audible. “How long?”

“A few minutes. See? Your breathing is better already.” The Doctor grinned. “Much better.”

“No.” Jack wiped the sweat from his forehead. “I mean…all of this. How long?”

“Two days. Maybe three.” The Doctor shrugged. “I don’t know. I’ve never seen this happen before; I only read about it once. Doesn’t happen very often. Most humans have the sense not to go near Wronskians.”

“But…why?”

“Not sure. Maybe the blue scales, huge black wings, and beady red eyes scare ‘em off.”

“Didn’t…work…on me.” Jack was shivering so hard the bed was starting to shake. “I thought…he was…kind of…sexy, actually.”

“Hm.” The Doctor patted Jack gently on the head. “And he gave you some very sexy parasites as a goodbye present. Very sweet of him, I think.”

“Wait.” Jack’s grip on his hand tightened. “Was going to ask before, but…forgot.” He coughed; immediately, his other hand was back on his chest. “Is this…contagious?”

"Rose will be staying away from you for a while, yes."

"No. Not to Rose. To you.” Jack flipped over onto his back; beneath him, the Doctor noted, the sheets were already soaked with sweat. “Can…can you catch…this…from me?”

"Nope." The Doctor grinned. "The little critters don't like Time Lords. Just Wronskians and humans.” He paused. “Especially humans.”

"Especially…especially humans, huh?" Jack coughed painfully. "Just my luck.” Then, after a long pause, he added, “Well, at least…at least I won't be..."

"Won't be what?" Jack didn't reply, so the Doctor approached him, leaned over until his head was directly above Jack's.

"Won't be making you sick," Jack whispered, pulling the Doctor down towards him, "when I do this." And then, in a flash, the Doctor felt Jack's hot skin against his, and the other man's lips pressing up against his own. The Doctor returned the kiss. Then, slightly shocked by his own reaction, he moved back once more.

"You," he instructed sternly, "need to stop that and get some rest, or you’ll be here the whole week.” Jack looked up at him, eyes glittering with fever. “I need to go tend to the TARDIS. But I’ll be back in a few minutes."

"You'll…be back, huh?" Jack raised an eyebrow. The Doctor had to give credit where credit was due. He’d never seen Jack paler, and the sheet of sweat coating his skin certainly didn’t do much for him either, and yet, somehow, he still managed to look, well, good. After a pause, Jack went on, voice cracking painfully. “You’re not…gonna just leave me…for the TARDIS, right?”

“Nope.” The Doctor shook his head. “Wouldn’t dream of it. I’ll be back before you know it.”

“Well,” Jack replied, smiling weakly, “I guess…guess I'd better rest up then, after all."