"Where are the results of the matrix tests?" He asked to no one in particular. Dr. Jarlsen pointed to a computer screen, drawing Rodney's attention.

"Hmm," Rodney hummed, scrolling through the numbers. "The third one."

Dr. Jarlsen frowned. "But the second showed slightly higher maximum--

"It's also less stable," Rodney interjected. "This one," He continued, tapping the screen, "has both stability and good output. And it's more compatible with the most common elements in Atlantis's available water supply."

"Oh," Dr. Jarlsen murmured. "But we're building the dist--

"Do you want to put your safety and future existence in the hands of Kavanagh's creation?" Rodney inquired curtly. "Or do you want to trust that I know what I'm talking about?"

"Ok," Dr. Jarlsen said, nodding quickly. "The third version it is. We can start production immediately, provided the equipment is available."

Rodney grinned and closed the laptop, handing it to the man. "Oh, it's available."

The trip to Carson's lab was brief due to Rodney's clipped pace. He and Dr. Jarlsen found the doctor in deep discussion with one of his fellow medicine men, arguing about a vial of something that looked like blood. "Rodney?" Carson said, his attention drawn to the now-open door. "Dare I ask why you're here?"

"Oh, we're fine," Rodney said, heading for the equipment he needed. "We just want to--

"You want to what?" Carson squawked, putting his body in a protective stance between Rodney and his precious equipment.

Rodney rolled his eyes. "I think that the impending arrival of the Wraith would be justification enough for borrowing some of your stuff," He muttered, waving a hand towards Carson's laboratory. "We need to make up more of the organic matrix. Lots of it, and your equipment is designed to do that. Ours isn't. We've gone over this before."

Carson sighed. He should've been expecting this, right from the moment when Rodney walked in and asked him to analyze a sample of sparkly goo they'd found on the arsenic-water world. He'd done so, reporting back that it was a fascinating but not overly complex matrix composed of polarized molecules and stabilizers that very vaguely resembled cellular components. Rodney had been just a little too happy to hear that. Then there was the time he'd come in and wanted to make a few samples of said goo, using the same Wraith-onslaught argument. "How much, when and what happens when you break my equipment?" Carson knew his opposition was just for show, but he couldn't not stand up for a few principles, even when Rodney was most assuredly going to steamroller right over him.

Rodney briefly attempted to look hurt, but gave it up when Carson smirked at him. "Dr. Jarlsen has all the information, and you can have yourself or one of your own people actually handle the equipment if you want to waste their time that way. We just need the stuff in production yesterday."

Carson nodded his agreement and Rodney left, barking at a cowering scientist to not fuck up his first big, life-saving assignment. The skinny, bespectacled man that approached Carson held out a data pad as though the Chief Medical Officer might bite his hand off in the process of taking it. "None of that," Carson murmured softly. "We'll leave the biting to Dr. McKay. He's certainly good at it."

Both men grinned and settled in to review the production notes.

•••

John leaned against a support pillar and watched Kavanagh direct a group of Marines as they installed one of the power units Rodney and Zelenka had designed. He had to pay grudging--and tacit--respect to Dr. McKay, not only for designing a way to utilize the new tech they'd found, but for doing so as quickly as he'd done it. Barely a week had passed since they'd located the abandoned Taim'la settlement and as of this morning most of the Atlantis crew was busy installing seven generators throughout the city. Rodney hadn't wanted to trust people like Kavanagh with any sort of supervision, but it was going to take at least three days to install each unit, so they were forced to divide up the labor. John estimated that Rodney would be by to bitch at Kavanagh's performance within the hour. He'd been rotating around the city, tweaking and adjusting each installation.

Of course, McKay was also taking a lot of credit for the new power source, but no one was the least bit surprised. After all, McKay was his own one-person self-congratulatory machine. The facts that he'd been the one to actually discover the power source, and then figure out a way to use it on Atlantis, were just minor details. Or not so minor, John admitted. Still, he wasn't about to feed McKay's ego by actually admitting anything to him.

"You could help."

John straightened up as McKay's voice crawled over his shoulder. "I'm supervising," He murmured, nodding towards the Marines. "Making sure everybody stays in line."

Rodney rolled his eyes. "Sure, because Kavanagh might fuck up but you know what you're doing?" He turned to the group of men and women currently hunched over a series of electrical connections. "Dare I ask?" He shouted, making every one of them jump.

Kavanagh glanced over and blanched. "Thank god you're here--and might I just say I never thought I'd actually want you anywhere near something I'm working on--we've got a problem."

John expected Rodney to make some sort of snide remark and so he was surprised when the scientist simply walked over to the mass of tangled wires and circuit boards and began to move things around. He heard a few sharply worded expletives, but for the most part Rodney just stuck his head into the job and soon enough even John could see that whatever had gone wrong was well on its way to repair. Eventually Kavanagh joined in, although his role seemed limited to holding things as Rodney rearranged them.

"I think you can finish it from here," Rodney said, backing away from what was now an unshielded console full of glowing crystal plates, wires and traditional circuit boards. "Next time, call me before you start on a section of instructions you don't understand. If anyone had allowed current through what you'd built, all those crystals would've been destroyed and we don't have time to find more replacements right now."

John was still staring at the spot where Rodney had been standing long after the man had left. He idly wondered if someone was drugging the man, since Rodney McKay was never that reasonable. Maybe it was all that sleep he got a couple of days ago. John considered looking into tying Rodney to his bed every so often and forcing him to--

With a firm shake to his brain, John stopped thinking about that and went back to watching Kavanagh berate his helpers.

•••

Rodney stared longingly at the corner of his lab. If only he could go over there and hide for a few minutes, just to avoid the dozen or so people who wanted his attention. He and Zelenka had just finished supervising the initial installation of the new generators and there was nothing Rodney wanted more than a few hours of sleep. Unfortunately Dr. Weir had figured out that there was a brief gap in Rodney's official working schedule, as the organic matrix wasn't yet ready. As a result she scheduled a series of something called contingency meetings, and she expected Rodney to be at each of them. He had attempted to explain that he did have other things he needed to do and she had countered by saying that she needed him to these other things she'd decided were more important.

Those other things turned out to be excruciatingly boring meetings. At least John had been at most of them, so they were able to pass notes back and forth and make stupid faces at each other. Rodney had also been able to devise a way to reroute some power to different parts of the city--an idea he was now testing out for its prospects as a power-saving technique. It was looking promising.

"Dr. McKay?"

Rodney turned around to see what Dr. Jarlsen wanted. "Is something about to kill everyone in the city? If not, I'm busy."

Dr. Jarlsen bounced from foot to foot, almost ignoring the way Dr. McKay was glaring at him. "The last batch is done."

"The last...show me," Rodney said, already walking to the door. Jarlsen had estimated it would take five days to produce all the matrix they'd need, but he'd ended up taking an extra 18 hours and Rodney was getting worried that they wouldn't get the system functional before the Wraith arrived.

The actual installation was pretty much finished and Rodney, with Dr. Zelenka's help, had spent most of their working hours scouring Atlantis's systems, trying desperately to find ways to cut down on power consumption. There had been several real breakthroughs that had dropped their power demands significantly. The single biggest success was Dr. Zelenka's rerouting of a set of solar panels they'd found lining one side of a tower. The panels didn't produce nearly enough energy to run the shields, but it was enough to keep the desalinization system running, provided the occupants of the city were frugal with their water usage.

When Rodney and Dr. Jarlsen arrived in the annexed medical research lab, they found Dr. Beckett and several of his assistants hovering around their precious equipment, obviously ready to confiscate the things. "Hold on, Carson," Rodney muttered, picking up a scanner and turning to the many vats of glittery, glowy goop that sat around the room. "If any of these are contaminated, unbalanced or otherwise fubar we're going to be making more."

"They've all fallen well within the parameters you set," Dr. Jarlsen said, fiddling with a second scanner. "We even made a little extra, just in case."

Rodney ignored him in favor of the output his scanner was providing. They had had to do some sophisticated guesswork as to the proper structure of the organic matrix, since even the most functional-looking bits they'd located planetside had been contaminated with arsenic. The contamination had destabilized the material to the point where it wouldn't generate current so Rodney and his team were forced to experiment with different variations they designed from guesses as to what the undamaged matrix would've been. They'd found four likely formulations, each one producing similar outputs with similar stabilities under stress conditions. In the end they'd selected the one that withstood the highest sodium and magnesium concentrations, as these were the two contaminants most likely to enter the systems from Atlantis's water. To be on the safe side, Rodney had ordered several engineers to design and build a distillation system exclusively for the matrix power generators.

After three hours of evaluation, Rodney was as confident as the situation let him be that the matrix was ready to go. He wasn't altogether sure that the system would provide enough power, since the best calculations they'd been able to make carried fairly large margins of error. In a more controlled situation he would have declared the entire idea unacceptable, but this was no controlled experiment. They only had one chance to make the shields work, and right now this system was their best bet.

They'd designed the generators to fully power the shield at 85% of maximum capacity. It wasn't optimal for their long-term power needs, but there were limitations to the matrix system that they hadn't had time to overcome. If the individual generators were built any larger, they would start losing efficiency as they grew unwieldy. They also had to deal with their own hardware shortages--an extensive search of Atlantis had barely produced enough material to make seven generators, and had taken up almost all of their electrical supplies. Carson would be bitching about his equipment for weeks, and Rodney truly hoped no one came up with an urgent need for phosphorus, antimony or carbon. They were currently out of those elements, and Rodney had serious doubts about their ability to run out to the Pegasus Galaxy 7-11 to pick up more.

"Alright," He said, snapping himself back to full alertness. "They're all acceptable." Everyone in the room cheered, and Rodney managed a self-satisfied smirk. Then he was back to his usual sneer. He tapped his headset and began barking orders. No one was going to sleep, or do anything else, until the generators were functional.

•••

John watched as Lt. Ford and Sergeant Bates carefully poured the glittery, slightly glowy goop into the main cell of the first generator. Rodney and Dr. Zelenka were watching on, occasionally hissing and wincing. The stuff was dense and heavy, so neither of them actually wanted to do the lifting themselves. "If you spill that, I'm going to kill you," Rodney said to Ford, who grinned.

"I'm not going to spill any," Aiden said. "Trust me."

Rodney snorted. "Ok, you've filled it enough--or didn't you notice the carefully applied 'fill to here' sign?"

Ford and Bates tipped the vat back up and carried it back down the ladder they'd been on. Zelenka climbed up and refastened the generator's cap, carefully making sure all the necessary nodes and connections were fully immersed in the gelatinous stuff. "It's secure," He told Rodney, coming back down to join McKay at the control panel.

Rodney began initializing the generator, cursing under his breath as a variety of ominous-looking things flashed up on the display.

"That doesn't look good," John commented as Rodney's fingers flitted over a control panel. Rodney paused, read a few lines of what was on the screen, and went to one side of the control panel and popped off a cover. He withdrew a crystal panel and waved it at Zelenka.

"It doesn't look like anything," Rodney spat, motioning to Zelenka for a new crystal plate. He used the new one in place of one with a hairline fracture in it and then began pressing keys on the control panel again.

"Which is bad," John replied, "Since it's supposed to be--

"Doing that," Rodney interjected as the control panel lit up. A moment later, a faint blue-grey glow began to creep through the organic matrix. Rodney's attention shifted to the output reading and he began to mutter, still adjusting some of the generator's controls.

"Well?" John asked, taking a few steps closer to the thing since it didn’t look like it was about to explode. "Is it working?"

Rodney ignored him in favor of barking at Zelenka. "Check the inputs, for chrissake. The current is fluctuating too much."

Zelenka went around to the back of the generator. "Ah, yes. Someone installed this bit backwards..." A few more words drifted around the generator, but they were in Czech and John had no idea what the man was saying. He had a feeling it wasn't polite or generous, though. "Try now," Zelenka called out after several minutes of cursing and thumping.

Rodney tweaked the settings a few more times and actually cracked a smile. "That did it, more or less," He declared, taking a step back from the control panel. "One down, six to go."

"So it works, right?" John asked, trying hard not to stare at the eerie matrix. The stuff would've been right at home in a psychedelic lounge, all glowy and goopy and blacklight freakish. He sort of wondered if random bits of static electricity would start arcing through the stuff eventually.

Rodney nodded. "It's not quite up to where we wanted it, but it's high enough to get the job done. If we're careful," He replied. "We may have to turn off some of the less-necessary functions around the city, or see about recalibrating all seven generators once we've got them all online."

John nodded and followed Rodney away from the generator, stopping briefly to order two Marines to stand guard around the newly functional system in case someone got it in their heads to mess with Rodney's new babies. He wasn't taking any chances with them, even if it meant putting a strain on their work rotation.

The next six generators were easier to fill and initialize, but it still took far too long to get them started. By the time Rodney was ready to test the shield, John had had to begin bringing the Athosians to the city.

"Dr. Weir? As soon as the Major gets into the 'jumper bay, we're going to turn the shield on," Rodney said, his eyes fixed on a diagram of the city. She watched along with him as the dot indicating the last 'jumper out slowly entered the city. It wasn't even fully stopped before he began turning the shield on.

"How’s the power?" He asked Dr. Zelenka, who was monitoring the city's power usage.

"Maybe where we thought it would be," Zelenka said. "Is just under capacity."

"Well, Dr. Weir," Rodney began, the beginnings of a smile creeping onto his face, "For the moment, at least, we are shielded."

A tentative, but relieved cheer rippled through the people grouped in the 'gate room and Rodney's team finally let themselves relax for a minute. Weir headed for the 'jumper bay to let the Major know the good news.

Elizabeth watched anxiously as the last of the Athosians stepped out of their puddlejumper transport and were guided away to their temporary quarters. She couldn't help the feeling of impending doom that kept chipping away at her well-honed optimism, not when so many lives depended on so many educated guesses. If the shield worked and held, if the power generators didn't malfunction, if the increased population of Atlantis didn't put undue stress on their meager supplies. Elizabeth was beginning to hate the word 'if'. It kept hounding her at night, paired up with its favorite companion, 'what'. What if the shield required additional energy when it was fired upon? Dr. McKay was their expert on Ancient technology, but that was a relative position; no one knew very much about it so he got the title by default.

What if this wasn't enough? They had an alpha site, but it wasn't optimal--the abandoned Taim'la city would work for a while, but if they had to evacuate to that location, they would be forced to move the entire city to escape the endogenous water contamination. The best clean water location was more then ten kilometers away from the stargate, which was anything but convenient.

She sighed and squinted in the dying sunlight, wishing not for the first time that their power rationing hadn't included nonessential lighting. Dr. McKay's tests had concluded that the shield would protect the city from most types of attacks, including chemical and biological warfare, which he deemed satisfactory proof that the city didn't absolutely need climate controls. Elizabeth had been prepared to protest that they couldn't expect everyone to live by the whims of the planet's weather when she realized just who was offering up that sacrifice.

If Rodney McKay was suggesting they cut off their air conditioning, then the power situation had to be truly grave. Once she'd taken a hard look at his complete list of power rationing protocols, she began to understand what he'd been up against in trying to find a way to power the shield. They were running the desalinization systems at a level that barely provided enough water for drinking and bathing and he'd found a way to reroute grey water to nondrinking functions, to lower their dependency on power-hungry fresh water. The lights, of course, went away, as did the climate control. For the time being, he suggested everyone learn to open their windows. He'd even suggested that they leave their doors open as much as possible, both for air circulation and to cut down on the power usage involved in constantly opening and closing them.

Frankly, she was surprised he hadn't recommended they string up clotheslines and start doing their laundry by hand. Then again, she was a little afraid that if she looked too closely, she might just find it somewhere in the section labeled 'extraneous activities.' He'd even eliminated computer usage of his own staff by a third, instead ordering them to plan out as much as possible by hand before using up power by booting up their computers.

Still, they had the shield--for now, anyway.

"Major," She began as Sheppard appeared outside the 'jumper. "You made it just in time."

John nodded and grinned. "The shield's up." He'd felt it as soon as it had come on--a low-level buzz behind his eyes. It was probably a side effect of being in the 'jumper, since flying into the shield wasn't the best idea.

Dr. Weir hadn't thought of that and looked surprised. "Yes, it is," She said, a little deflated that her good news wasn't exactly a surprise. "Rodney's trying to make sure it'll hold long enough for the Wraith to come and go."

John nodded again and turned to find Rodney. He needed to talk to the man and find out just how little power could be used, and exactly how sternly he needed to remind his men not to do anything they'd been told not to do. Dr. Weir didn't seem to be about to say anything else, and Teyla had just arrived with a rather serious look on her face, so John made his exit gratefully.

When John got to the control area, Zelenka was studying the display, but Rodney wasn't around. John glanced at the 'gate room and caught a glimpse of McKay standing on one of the balconies, looking at the ocean. He walked across the large room, skirting the inactive gate, and paused at the opening to the balcony. His P90 was digging into his side, so John shifted it, making enough noise that Rodney knew he was there.

"I wonder if this was how the Ancients did it," Rodney mused, staring out into the inky darkness of a moonless Atlantean night.

"Did what?" John inquired, stepping out onto the balcony to join him.

Rodney looked over at the Major, who appeared more heavily armed than usual. "Waited for the Wraith to arrive. Did they raise the shield and stay on the surface, or just sink into the ocean?"

John shrugged. "No clue, but you'd think they'd just go underwater. Makes less of a target that way."

Rodney nodded. "You do realize that if the shield holds, you won't be shooting at anything?" He commented, gesturing towards the Major's rifle. "That's a bit pointless."

"I always carry this," John reminded him.

"Not with that much ammunition," Rodney said, smirking. "Although I wouldn't blame you if you used it on those people." He waved one hand towards the interior of the city, where a few dozen people remained despite orders to the contrary, anxiously awaiting their fates.

John grimaced. "They're not so bad," He said, not convincing himself, much less Rodney.

Rodney snorted. "They're so scared the air stinks with it," He spat, shaking his head in resignation. "Our people can't decide whether to shit themselves or run screaming and the Athosians are almost expecting to die."

"And you're the picture of quiet confidence," John retorted. "Chicken Little."

"You know damn well that if I start yelling about the sky falling, it's really falling down around your ankles," Rodney muttered, turning to go back inside. "That I can promise you."

John stayed outside a while longer, wondering if the Wraith would go for the dramatic and attack in the dark of night, or wait until the next morning. They were already in the system, hovering just beyond the planet's farthest moon. The exact moment of when was irrelevant, though; somehow John knew they wouldn't see the next evening without an appearance by the Wraith.

•••

Rodney hadn't bothered to try to sleep; despite his now-constant exhaustion, he was too nervous. Daylight was approaching and the Wraith were still out there. The long span of darkness between the shield going up and the coming sunrise had been nerve-wracking for everyone in the city. Rodney himself wondered if he'd developed an ulcer or three.

"Where are they?" Kavanagh asked, his eyes dancing between the sensor display and the shield status indicator. "Why haven't they attacked us?"

"Maybe they know the shield's up," Lt. Ford offered as he and the Major paced in front of the stargate. "And they're hanging back, waiting for us to shut it off."

"Or maybe they just haven't gotten around to trying to blow us to smithereens," Rodney said, rolling his eyes. "Since I managed to mislay my 'Wraith Invasion Strategies' handbook in the same place I put my 'never-ending power supply', I can't tell you for sure."

"Rodney? Snark not so good right now," Major Sheppard warned, glaring at the scientist. Dr. Weir had ordered most of the civilians to interior locations in the city, while the military were placed in defensive locations in case the shield didn't hold. Still, the residents of Atlantis managed to crowd into the gate room, sitting in small groups as they stared out into the early morning blackness. John privately found the deathwatch more than a little unnerving. It was one thing to be a guy with a rifle, standing guard. It was another thing entirely to just sit there like a sheep waiting to be slaughtered.

"McKay!"

Sheppard, McKay and Ford turned as Dr. Zelenka came around the control booth, waving anxiously. "It has started."

They ran up the stairs, meeting Dr. Weir as she began to address the city. She gave a small spiel over the speaker system while everyone else watched the monitors as a flight of Wraith darts approached the planet.

"How many are there?" Sheppard asked, staring at the screen.

"Dozens," Rodney replied, his hands gliding over Ancient controls. The city, already mostly dark, fell into eerie shadows as he cut the rest of the lighting. Anyone who wasn't where he was supposed to be was stuck now, unable to see more than a few feet in any direction. The lone monitor now glowed dimly, showing the approaching Wraith darts.

Sheppard monitored the constant reports from his troops as they stood guard over the seven power generators, as well as several dozen posts both in the city and on balconies. If the shields held, their jobs would be easy--nothing more than listing and/or watching the Wraith fail to breach the city. If the shields fell...

He didn't want to think about the possibility.

As the tiny dots marking the Wraith drew closer, Sheppard turned from the display and went out on the nearest balcony, looking up to the night sky. He stared out, trying to see the incoming darts amongst blinking stars and thin, high clouds that left grey slashes on an inky sky. He saw nothing, heard nothing but the soothing slap of water on metal and the muted patter of footsteps behind him.

"Here," Rodney said, handing John a pair of field glasses.

John took the glasses and let Rodney orient him on where the Wraith should appear. He'd barely focused them when the first dart came into view, a silver flash hurtling directly at him. Dozens more passed through his limited vision and he dropped the glasses, head whipping back as the Wraith flew at his face.

And ran directly into the shield, cracking and exploding as through they'd flown into a mountainside. He'd wondered once what such a collision looked like from the mountain’s perspective, and now he knew. The first four darts had obviously not anticipated the shield and ran right into it, exploding on contact. The shield shimmered and the remains of the darts fluttered down to the ocean surface, flames flickering here and there.

The rest of the darts pulled up and circled around, firing at the city. John felt, more than heard, Rodney turning around and retreating, probably to check on the shield's status. John could've told him, though, that the shield was holding. Watchful eyes catalogued each hit, each time the shield made that shuddering flicker and each time was as quick and bright as the last.

The darts fired sporadically for another few minutes before grouping together and flying back the way they came, disappearing as quickly as they'd arrived. All that remained of their brief attack was a quickly sinking stripe of debris and the ringing in John's ears from a few dozen ineffective shots.

John returned to the 'gate room, where he found a lot of very anxious people. Their insecurity was understandable; were the Wraith really retreating? Was the shield holding? John could almost taste the adrenalin in his blood, thin and bitter like gasoline. He was wired, waiting for a battle that he was increasingly sure wasn't going to come today.

"Major!" Rodney called out from the control area. "The Wraith are moving back." A series of muted cheers rose from the exhausted, neurotic crowd in the 'gate room, and it took John several minutes to make his way through the increasingly active throng.

"How far back?" John asked when he reached Rodney and the display.

Zelenka and Rodney turned at the same time. "Not far enough," Rodney muttered, pointing to the hive ships on the display. "They went back, and then stopped."

"Like vultures," Dr. Zelenka added. "Perched above the city."

John studied the display. A small dot came onto it, flying straight for Atlantis. "They're still sending darts," He said, watching as the dart flew over the city, fired a few times and then circled back around to the hive ships.

"They're testing the shield," Rodney replied.

"If you came all that way, would you just turn around and go home?" John asked. "If there was a chance you'd get a second shot at this place?"

Rodney's attention shifted to the shield indicator. "As long as the shield's up, it doesn’t really matter."