Divide and Subtract

[paranoidangel42]

Title: Divide and Subtract
Author: paranoidangel
Rating: PG
Words: ~4000
Summary: Back before John Sheppard had ever heard of the Law School, he and Rodney McKay weren't always friends...
Notes: Much thanks to wannatee_1984 for betaing - it wouldn't have been as good otherwise.
This is inspired by mine and my dad's maths arguments (he thinks it's great, I think it's useful) and by Grace Under Pressure, although there are no spoilers for that episode.
I feel slightly guilty as no-one else has posted any fic since my last one - I don't usually write this fast! (it won't last, don't worry *g*)
Feedback: Is all appreciated, no matter how short or long. Praise expands my ego, concrit helps me improve.


Doctor John Sheppard approached Newton Hall with some trepidation. It was hard enough getting excited about teaching math to students who had no interest in it but he had discovered that teaching it to physicists was actually worse. They had no appreciation for the finer points of the subject, unless he related everything he taught to physics which irked him to no end. Most of the things he said seemed to go in one ear and out the other, except for when one of them asked "but what's it for?", which came regularly. He already dreaded every lesson and he had only been teaching this class for two weeks.

He had done a fair bit of physics back when he was a student but that was because he could apply it to airplanes. In the end he had preferred math and doing research for 'Math for Scientists' only reminded him why. On the one hand he would like it if these students just valued the math knowledge they needed and, more importantly, learnt something from his lessons, but on the other hand he would not be too upset if this experiment was not a success at the end of the semester.

The only good thing about the course was that the physics building was next door to the math one - though for some peculiar reason the weather seemed to have it in for him every time he went there. On Monday it had started raining the minute he put his foot out the door. Today it was mercifully dry but blowing gale force winds instead, even though it had been warm and sunny when he left his house earlier that morning.

He pulled his jacket tighter around him and clutched his briefcase to his chest, lest it should fly out of his hand. When he opened one of the side doors of Newton Hall he was nearly pulled away with it. Getting himself inside and closing it behind him was something of a trial and already John was wishing he did not have to teach this class - he usually lasted at least until he was actually in the class before he was cursing it. He was certainly not intending to do it next year if he could possibly find a way of getting out of it.

The one bright spot, and the reason he left early for this particular class, was an opportunity to talk to Rodney McKay, the man who should have been taking it but apparently thought his time could be better spent elsewhere, rather than with actual teaching. Although he was obviously not too busy to butter up Doctor Hall by telling him how much better the mathematicians could teach the subject than he could. It was, he learned, the only time anyone ever heard Doctor McKay admit there was anything someone else could do better than him. Having met the man John could well believe it and always took the opportunity to pay him a visit and annoy him as much as possible, which admittedly was not hard.

Having run his hand through his hair and gone up the two flights of stairs, John reached Rodney's office. Opening the door without knocking, he burst in with a jubilant shout of "McKay!"

There was a grunt and a mumbled "Sheppard" in response. Rodney did not even look up and continued his typing at a frantic pace on the two computers positioned next to each other on a table along one wall.

John waited patiently. It did not take long.

Rodney sighed and swivelled round to face John. "Look, I'm very busy here, do you want something?"

John casually leant his hip against the desk nearest the door. He might have sat on the edge of it but he could not see enough of its surface to do so. "No, not really. Just dropping in to remind you I'm here to teach your students."

"Well, get on with it and try not to rot their brains too much."

"I'll do my best but they do seem to be under a misapprehension that they can be physics majors without actually learning any math."

"They're students, they don't know anything. Now, leave me alone, I have a lot of work to do." Rodney waved a hand at him, as if to shoo him away, and turned back to his computers, scowling.

It was nearly the same conversation they had every week, although it was sometimes enhanced by a pure math 'discussion', depending on how much time John had before his class started and how busy Rodney was pretending to be. John would have found something else to wind the man up with but he did not know him well enough yet. So for now they pretty much stuck to the established script. "It was nice to see you too, McKay." He was just opening the door when Rodney called him back.

"Sheppard, have you got a minute?"

John was too stunned that Rodney was actually being civil that he could not say anything for several seconds. By the time he managed to connect his mouth and brain, Rodney got there first.

"Look, I need someone's help and half the department's off with flu and I promise you'll still make your class on time--"

John held up a hand and cut him off before he could go any further. "Okay, I'll help. What do you need me to do?"

"Follow me."

John moved aside so Rodney could exit his office first and wondered, bemused as to what he had got himself into. Or just why he was doing a favour for a man who went out of his way to insult both him and his subject at every opportunity. Okay, so John gave as good as he got, and he had to admit he quite enjoyed arguing with Rodney, but that had been their entire relationship until now.

As they walked, Rodney muttered to himself whilst leafing through pieces of paper that were variously folded up, stuck in his pants pocket and then pulled out again. John did not know Newton Hall very well so he tried to concentrate on where they were going. After having got lost the first few times he now knew the way from the entrance to Rodney's office, to the lecture hall he taught in but that was it. Rodney led him along so many twists and turns that he wondered if he was purposely trying to get John lost. He was entirely confused, though, when they were suddenly outside once more, because John was sure they had not gone down the same number of flights of stairs he had gone up.

It looked like they were in some kind of quad as it had benches to sit on among the small patch of greenery and a pond towards one side. Except that this quad only had buildings on three sides. The open side was handily acting like a wind tunnel, so now John was almost blown over and he could no longer hear Rodney, who had quickly put his papers away while fighting to keep hold of them. John was quite glad when he was hustled through a big, heavy door.

He found himself on a small landing at the top of a flight of stairs, mercifully out of the wind once Rodney shut the door behind them. A dim light came on with the flick of the switch and John could see they were in a basement. Although physicists must have a funny idea of what a basement was for because this one was full of equipment, much of it blinking. The whirring sounds it all made seemed quiet compared to the noise of the wind he could still hear whistling through the gaps.

"You have to go outside to get to the basement?" he asked Rodney as they descended the steps.

"It's a designers dream."

John gave a wry grin in response, even though the back of Rodney's head was the only part of him that could see it.

Once he was at the bottom of the stairs there was a much more obvious musty smell that John could not quite place. Given the convoluted trip they had made to get here he wondered how much it was used.

Rodney led John over to a bank of equipment in one corner, which had lots of wires plugged into it and lights in at least four different colours that he could see. John thought it could be some sort of supercomputer - it was certainly cold enough - but it did seem an odd place to put one.

"Now, when I say, pull this one down," Rodney said, pointing at one of the switches and miming the movements as he said them, "then that one up and then press this button. Got that?"

"Yep." Rodney moved away and John stood in his place. "What do they do anyway? I'm not about to turn the power off for the entire building or something, am I?"

"Yes, because I want to be down in the basement in the dark with you."

John rolled his eyes. "Likewise."

Rodney gave no indication of heaving heard and he had already moved to another tower over in the opposite corner and pressed some buttons on that one. "Now," he said and John performed the actions Rodney had shown him.

"Ummph! Okay then," Rodney said afterwards, looking up at some flashing lights that were presumably telling him something, "you can go now."

John almost said something but Rodney seemed absorbed in taking readings and writing the results down in the notebook he pulled out of his pocket. It seemed like Rodney's short-lived good mood towards him had evaporated. Rodney McKay was certainly the eccentric physicist the stereotypes made him out to be. John decided to do as he was told and make an attempt at finding his class on his own, before he was actually late, rather than merely fashionably so.

At least, that was the plan. Unfortunately, when John twisted the handle on the door and pushed it, nothing happened. There was not much light at the top of the stairs so he felt around for any other locks or handles he might have missed but all he found was cold, damp wood. A bad omen. Just what he needed.

"McKay!" he shouted down, "I can't open the door." He felt stupid as he said it.

"Oh my god, I know mathematicians have no idea how to do anything practical but even you should be able to open a door on your own," Rodney grumbled as he trudged up the stairs and elbowed John out of the way.

John could not help but smile when Rodney had the same problem he did. "Put some muscle into it," he suggested.

"A little help would be nice."

John braced himself against the door. "1..2..3," and they both pushed as hard as they could. Still nothing happened.

"Great!" Rodney said, as he turned and sagged against it.

"We'll just have to wait for someone to rescue us." John could not help but smile, as much as he hated the situation.

"Except that no-one knows we're down here!"

"I have a class in," John checked his watch, "five minutes! So someone will miss me."

Rodney folded his arms. "Are you implying that no-one will miss me?"

"Now, now! I didn't say that," John said, putting his hands out in which he hoped was a placatory gesture, although he could not say why he was bothering to try.

"They'll never look for you down here, though."

John sighed and hit the back of his head against the door, wishing Rodney was not such a pessimist. Not that John really wanted to be stuck down here, and certainly not with Rodney, but he was not entirely unhappy to be missing class. "Look on the bright side, at least we have light."

"Don't say that, that's just asking for it to go out!" Rodney glared down the stairs at the small bulb in the centre of the ceiling, as if daring it to think about it.

John rolled his eyes and pulled out his cell phone. No signal. He got closer to the door and held it up to the small crack at the top. For a moment, it looked like there might have been something but it went again before he could be sure. Shaking it did not seem to make any difference. "Damn," he said, putting the phone back in his pocket.

He had to look at Rodney for a good long time before he got the message. "Mine's on my desk," he said, morosely.

John sighed again, out of options this time, especially as Rodney did not seem to be about to contribute anything useful, so he went back down to the basement to wait. There were no chairs but there was a small space of wall mercifully free of any equipment, so it was at least something to lean against. He would have taken his jacket off and sat on it but it was not really warm enough. He leaned his head against the wall, closed his eyes and tried to think of a way out of the situation. Rodney was too distracting, though, as John heard him thump his way down the stairs slowly, then sound like he was falling the last few.

His eyes snapped open in time to see Rodney picking himself up off the floor. "You okay?"

"Yes, yes, fine, apart from probably breaking my ankle. And I'm not very good with enclosed spaces."

Given that Rodney was standing relatively happily John suspected he was exaggerating about his injury, so he ignored the first comment and concentrated on the second. "It's quite a big enclosed space."

"Yes, that helps, of course, why didn't I think of that?"

John shrugged but Rodney made a great show of hyperventilating while limping and rubbing one elbow. "For goodness sake, McKay, sit down, you're wearing me out."

Rodney gave him a look but did as he was told, plopping himself down only a few inches away from John, his back against the wall.

"Now close your eyes, take a deep breath and imagine you're on a desert island."

John was almost shocked when Rodney did as he suggested. Well, at least he closed his eyes and breathed more evenly, the desert island part he had no way of being sure about.

"Where did you learn that?" Rodney said after a few deep breaths, not yet opening his eyes.

John guessed his question meant it was working. "When I was a kid," he said. He was not prepared to offer any more information than that and fortunately Rodney did not ask.

"Sam Carter," he said, instead.

"What?" John asked, not following. He turned round to look at Rodney more closely, not that it helped.

"What I'd take to a desert island."

John smiled. "I don't think you're allowed to take people."

"It's my desert island."

"Fair enough." He leant back against the wall, which only served to remind him how cold it had got - he could feel it, even through his jacket. "In that case I'd take a plane."

Rodney opened his eyes and turned his head to look over at him.

"It's a big island!"

Rodney smiled in response this time and John thought he heard a muttered comment of "mad mathematicians" but he could not be sure.

"I thought Sam Carter hated you," John said, changing the subject slightly. This was a more interesting, not to mention, different topic than their usual math arguments and if they had to spend some together in a small space with no other distractions he did not really want to get onto those.

Rodney sighed. "She does, but a desert island would get cold at night so we'd have to huddle together. For warmth."

"Ah, I see." He did think Rodney was perhaps over thinking this desert island thing a bit but then given that he knew what type of plane he would have and the best place to put the runway, he did not voice his thoughts. "But in the absence of a desert island...?" he asked. He might as well get some useful gossip while he was stuck down here.

"I'm pretty much screwed. And not literally either."

John chuckled. His own love life was currently nonexistent, though, so he was not really in a place to comment. "I think," he said, "I'd rather have Buffy."

"Than a plane?"

"Than Doctor Carter. With me on a desert island, I mean, if there are predators at least Buffy would be able to fight them off."

"Don't be so sure Sam wouldn't. But yeah, I see what you mean. She could do all that kung fu stuff on any demons that thought I was food. Then, of course, she'd have to wash the demon blood off."

"Of course." John started to roll his eyes until an image of a half-naked Buffy intruded. "Isn't she a bit young for you?"

"Speak for yourself! Actually I think Sarah Michelle Gellar is in her twenties. So it's not quite cradle-snatching."

"You're the one who likes blondes."

"Buffy was a brunette in the unaired pilot. Didn't you see that?"

"Um, unaired, McKay?"

Rodney waved his hand like that was an unimportant detail. "Internet."

"Ah. I don't suppose--"

"Hidden on the university network, I'll e-mail you the link."

"Thanks."

Having managed somehow to effectively kill the conversation, John was considering if it was possible to have a late morning nap while sitting up when he was conscious of Rodney shivering next to him. Not that Rodney was ever still for very long but he was certainly past the panicky point. He pulled his jacket off and crouched down while he spread it on the floor. When he had sat down on one half of it he patted the other side and Rodney, who had been looking at him suspiciously up until that point, shifted over.

There was not much space for them both to sit and avoid the cold wall, so their sides were pressed together. John could feel he was warmer than Rodney, although that probably would not last now he no longer had an extra layer on. He wished this had happened later in the semester, although he did not know how hot this place got in the summer.

"You know what's happening, don't you?" Rodney's voice sounded suddenly loud after the silence.

John had no idea what Rodney was talking about but that had not exactly been a novelty in their conversation so far. "No."

"We're living a cliché! Two people who hate each other get trapped together and come out friends."

Rodney had a tendency to talk with his hands, which was fine for his right but meant his left hit John in the thigh more than once. Rodney either did not notice or did not care. John was surprised to find he did not mind as much as he thought he would have earlier this morning, considering this was a man he did not actually like. "We are actually having a civil conversation without insulting each other," John conceded, "and we do seem to have things in common."

There was a pause.

"We should agree not to be friends when we get out of here," Rodney suggested.

"Works for me."

"Okay."

They made an attempt at shaking hands without moving and, in John's case, only using his right arm below the elbow. Their hands definitely met, though, so that counted. Barely had they done so when Rodney leapt up and John felt suddenly cold.

"I'm an idiot!"

"Er...yeah?" John tried.

"There are computers in here, connected to the network!"

"You really have computers in the basement?"

"For experiments," Rodney answered, but was over at what John belatedly realised must be a terminal, and Rodney was not really listening any more.

After some typing, and swearing, Rodney sighed and stepped back. "We're being rescued."

"Thank goodness for that," John said, picking up his jacket and shaking it out before putting it back on. It was nice and warm on the inside. Rodney was already making his way up the stairs and John followed him. At the top, Rodney bounced on his feet, his hands in his pockets. John leaned against the door for a minute before it occurred to him that once it was opened he was liable to fall through it. Plus his shoulder was getting damp.

John had to try hard not to start another conversation that could end up with them being friends, or worse, enemies again. Not that either would stop him from trying to annoy Rodney the next time he taught Math for Scientists. "How long will it be?" he asked. There was only so much standing around in silence it was possible to do before boredom set in. "I'm starving."

"Not long, I hope. Although I did forget Zelenka's name again this morning, so he might not rush necessarily."

"Great." John gave up and sat on the top step, his arms resting on his knees and his head slumped over them, the small adrenaline rush of false hope having run out.

Rodney sat by him before looking at his watch. "The cafeteria will have just started serving lunch. And Wednesday is steak day."

John's head snapped up. "Hang on, you have steak in the physics cafeteria?"

"Yes. You don't?" Rodney sounded innocent, but John could tell he was anything but.

"We don't even have a proper cafeteria, just a little place that sells sandwiches."

"So, our building is much better than yours."

"Oh, I didn't say that."

Fortunately for both of them there was a scraping sound outside and they twisted round, neither wishing to get up before it was certain they would be going somewhere. Unfortunately, they both turned towards each other and John's knee hit Rodney's with a crack. John winced at the sound.

Rodney slapped his hand over the spot and glared at him. "Why don't you kill me just as we're about to be rescued?"

"Don't be so melodramatic," John replied, rubbing his own knee. He would have a bruise there tomorrow.

The door finally opened to reveal Radek Zelenka on the other side, looking pityingly at John, at which John smiled and Rodney scowled. John could have kissed Radek at his timing. Rodney just pushed past both of them complaining about his experiment being ruined but Radek was obviously used to that for he said nothing, merely nodded when John thanked him.

John followed them both, as he had no idea where in the grounds he was any more. He needed to reschedule his class and wanted to drag Rodney out of his office to show John where the steak was. The next time he went into a room with Rodney, though, he would make sure either the door stayed open or there were other people in it first.