A/N: For the Men and Machines challenge at the sgaflashfic community on livejournal. Warning - this is slash (a man and another man kissing. How sinful.) - don't like, don't read. Disclaimer - takes deep breath I don't own anything to do with Stargate, Star Trek (especially Voyager), Andromeda and I don't own Mars Hewlett, although I might kidnap him if it gave me a chance to meet his owner. Feedback is better than blue Jello, but flamers will get an invasive medical exam.

If you don't understand this fic, read the post at the end.

Everything was dark.

Carson groaned and tried to wave a hand in front of his face, but none of his limbs seemed willing to cooperate. Vague grey shapes were beginning to form in his field of vision and his ears were starting to pick up the faint sound of humming machinery.

As quickly as if someone had switched on a light, the world came back to him like a slap in the face and he found himself in the novel situation of being a patient in his own infirmary, lying on one of the hard hospital beds. Thankfully, he was still dressed in his own clothes.

Memories began to trickle into his conscious mind as his eyes adjusted to the light. He had been in the lab… not his lab, Rodney's lab… which could only mean that his friend had been forcing some Ancient gadget upon him, wanting him to make the bloody thing work.

His thoughts were disrupted when a familiar man appeared in the exact centre of the infirmary and said in flat, authoritative tones, "Please state the nature of the medical emergency."

Carson stared. His mind was wondering what the hell Richard Woolsey was doing in his infirmary, so his mouth had to manage with, "Excuse me?"

Woolsey rolled his eyes and repeated, "Please state the nature of the medical emergency."

"Um…" Carson could clearly remember the man returning to Earth after the defeat of the Replicators in Atlantis. "I'm not sure there is an emergency, exactly." In fact, he'd most definitely expressed a wish never to return. "Might I ask what you're doing here?" he enquired, trying to stop the pounding in his head long enough to make sense of the situation. It was clear he was missing something vital.

Frowning impatiently, Woolsey came over and checked Carson's pulse. He was wearing the yellow uniform of the Atlantis medical staff. "Very funny," he sneered. "Make fun of the EMH for not being able to leave the infirmary. You humans have a warped sense of humour, I hope you realise that."

The feeling of being entirely out of his depth was starting to creep over Carson. "EMH?" he repeated weakly.

Sighing impatiently, Woolsey dropped the wrist he'd been examining and took a step back. "You're perfectly fine," he snapped. "Stop wasting my time and get out of my infirmary. And take the mutt with you!"

And then he disappeared again. Carson looked around the empty infirmary and reached up to touch his radio, but before his hand got there, a low growl from beneath him drew his gaze to the floor.

There was a dog staring up at him with teeth bared. It was kind of terrier-ish and had a dark brown coat and it was staring at him.

"Nice doggie." Now, the real question was: did he make a break for the door and hope to God the dog didn't eat him, or did he stay up here on this nice, safe hospital bed like a big girl's blouse until someone rescued him?

The dog barked once and saved Carson from his dilemma by turning tail and walking out of the infirmary. Just as it reached the door, it turned its head to look at him and barked once more.

"I must be crazy," Carson muttered to himself as he got up and followed the dog down a corridor in the general direction of the science labs. He was starting to remember what had happened in Rodney's lab, and the fragmented puzzle of the past few hours was coming back together, piece by piece. Everything was starting to make sense – the strange appearance of Richard Woolsey, the fact that he didn't seem to recognise Carson and this surprisingly charismatic dog. The downside was, understanding what had happened just created a new problem for Carson, and he had no idea how to solve it. All he cold hope was that this dog was leading him somewhere helpful and wasn't just hoping to be fed.

-----xxXxx-----

They ended up in Rodney's lab, which was exactly where it was supposed to be. This was just as well really, because Carson wasn't up to the task of interacting with more strange versions of people he knew than he needed to. Knowing Carson's luck, the Marines in this universe were giant cyborgs with laser cannons for arms, programmed to shoot anything unfamiliar.

The dog ran straight up to Rodney, wagging its tail furiously, and jumped up into his lap. Rodney turned away from his laptop and began fussing over the dog, scratching behind its ears and kissing is nose. After watching the two of them for several minutes with a huge grin on his face, Carson decided to make his presence known and knocked lightly on the wall to get Rodney's attention. The scientist looked up from his dog, obviously confused to see him.

"He wasn't anywhere he shouldn't have been, was he?" he asked, stroking the dog's head absentmindedly with one hand. "I've told him not to go wandering off, but he's pretty independent and I can't exactly put him in a cage. As soon as I'm absorbed in my work, he disappears."

"He was, uh, in the infirmary," Carson replied. "Look, um-"

"I suppose I should thank you for bringing him back, then," Rodney interrupted. "Take the rest of the day off, or something." Setting the dog down on the floor with a pat on the head, he turned back to his laptop and began typing furiously.

"Um…"

"Are you still here?" He didn't even look up from the laptop this time. "I'm very grateful you returned my dog, but I'm kinda busy right now. What do you want, a medal?"

"You don't know who I am, do you?" Carson sighed. If he wasn't a member of the expedition in this universe, it was going to be harder to convince people that he was telling the truth.

All he got for his trouble was a hand wave that suggested the motion of brushing away a fly. "There's hundreds of you, am I supposed to memorize names and faces?" Rodney said distractedly. "When you do something competent in your field, I'll make an effort."

"Rodney, I'm not one of your damn minions," Carson huffed. Did he say hundreds? Last time he checked, there were only eighty or so scientists on the expedition. "I'm from-"

"Wait a sec," Rodney turned to him with a slight frown creasing his forehead, as if he was trying to figure something out. "That accent… I'm sure I don't have a Scotsman on my team…"

"That's what I've been trying to tell you!" Carson snapped. "I came from an-"

"Shut up, I'm thinking," Rodney snapped his fingers in that impatient way of his. "And you seem to know me well enough to use my first name."

"Rodney's your middle name," Carson reminded him with a smirk, enjoying the way his friend's eyes widened in disbelief.

"How did you – that's not the point." Folding his arms, Rodney scowled at him. "You seem to know me well enough to know my real name," he amended, "Which suggests… best friend? Lover? You're not really my type, but-"

"We'll go with the first option," Carson interrupted hastily. "I'm from another universe," he added, by way of explanation.

Rolling his eyes, Rodney ignored the obviousness of that last statement and tapped his radio. "McKay to Atlantis. Come to my lab, there's something you need to see."

"Atlantis?" Carson seemed to be repeating parts of other people's sentences quite often today.

"You don't have the AI in your universe?" Rodney asked. "How the hell have you managed to stay alive? She's the only reason we were able to defeat the Wraith."

Now that was a very interesting piece of information indeed. If only Carson knew what to make of it. "We've only managed to keep the Wraith at bay," Carson explained. "They've culled a large number of planets and are still working their way through the galaxy. We're not even close to stopping them yet."

"Hm," Rodney looked immensely pleased to be in the superior universe. "We wiped out the last of them about six months ago. No one's been culled on anything near a planetary scale for at least a year."

"But… how?" If he could find out the secret to defeating the Wraith, ending up in this universe might be worth it after all. "If there's anything you can tell me, anything that all-"

"Yes, of course, all in good time," Rodney was looking past him now, nodding at someone in the doorway. "Atlantis will tell you everything you need to know once we've figured out how you got here and how to get you back home."

Turning towards the doorway, Carson recognised Dr Carolyn Lam, his counterpart at the SGC. She wore a red uniform similar to the one worn by Dr Weir and her hair was loose and just above shoulder length, rather than the customary bun Carson was used to. He'd spent some time working with her in the few weeks he'd spent at the SGC before that first journey to Pegasus, three years ago.

"How can I help?" she asked, a helpful smile on her face. A thousand questions sprang to mind before Carson settled on one.

"What are you, exactly?" he asked, hoping that the way he'd phrased the question wouldn't offend. It had occurred to him that 'who are you?' was probably the wrong way to go about asking.

"I am an interface between the city and its occupants," she explained. "A physical representation of Atlantis." Seeing his still-confused expression, she elaborated, "An Artificial Intelligence."

"Oh." Carson felt that his response was somewhat lacking, but how else was he supposed to react? "Um… you're human in my universe. You're the chief medical officer back at the SGC, on Earth."

Atlantis tilted her head inquisitively – a surprisingly childlike gesture. "How fascinating. What's my human name?"

"Carolyn," Carson told her. "Dr Carolyn Lam."

"I'm sure this is the most fascinating thing ever," Rodney interrupted, "But I have work to do, so can we just get him back where he belongs?"

"I'm sorry, am I making your universe untidy?" Carson snapped. This whole ordeal was very stressful for him and he didn't appreciate the feeling that this universe's Rodney wanted to sweep him under the rug and forget about him.

"There are several ways in which he may have found his way here," Atlantis interrupted before an argument could occur. "One possibility is a quantum mirror. A handful were left behind when the last of the Ancients left the city."

"Was it a quantum mirror?" Rodney asked, avoiding direct eye contact with Carson. The man was just as childish as the Rodney McKay in his own universe.

"It didn't look at all mirror-like," Carson said directly to Atlantis. Two could play at this game. "It was more like a-"

"Yes, I doubt that your universe's McKay would have been stupid enough to let anyone near a quantum mirror if he found one," Rodney interrupted smugly. "He'd have recognised it from the one in Area 51, if he spent any time working there like I did."

"There's a quantum mirror back on Earth?" Carson had no idea whether this was true of his universe. He'd never been to Area 51, had no interest in the potentially dangerous Ancient devices that were stored there.

"Daniel found it on a planet in your galaxy," Atlantis explained. "He discovered its purpose when he found himself in an alternate SGC where the Goa'uld had invaded your planet."

"You've met Dr Jackson?" Carson asked. "I assumed, since you'd said you were created as an interface to Atlantis, that you're not from Earth."

"That is correct," Atlantis replied. "But was Daniel not on the original expedition in your universe? I met him when he came here – he was the one who found me and activated me."

Shaking his head, Carson explained, "He was pretty desperate to join the expedition, actually, but General O'Neill wanted him back on Earth. He's never set foot on Atlantis… the city, that is."

"Oh. That is… disconcerting."

"Why's that? Are you good friends?" Carson asked.

"They've been married for, like, two years," Rodney told him impatiently. "It would be nice if we could stop digressing from the point every five seconds, by the way."

Fighting down the eyebrows that wanted to shoot up to the top of his forehead, Carson settled for an inquisitive look. "Married? But she's-"

"I am equipped with fully functioning-"

"Um," Carson interrupted before Atlantis could finish her sentence, "I didn't mean to cause any offence, love. It's just that… the only artificial intelligence we've ever come across are the Replicators."

Atlantis nodded. "In that case, I understand your concern," she told him, "But I am not built as they were. I do not have the same drive to replicate and unlike them, I am equipped with a full range of human emotions."

"Oh, that's what you were going to say."

Atlantis looked perplexed, but Rodney just rolled his eyes as if he'd heard this conversation a thousand times before. "Can we get back to trying to get rid of you?" he asked. "What was the last thing you remember before you arrived in this universe?"

-----xxXxx-----

Back in Antarctica, when there had been fewer people with the ATA gene to use as human guinea pigs, Carson had found himself dragged to Rodney's lab at least three times a day. Now that Colonel Sheppard was around, and Carson had managed to get the success rate of the gene therapy as high as 48, Rodney had switched to using his minions or the Colonel when he needed someone other than himself to activate something.

Which was why Carson's argument that there must be someone other than him that could turn the bloody thing on was completely valid. Nevertheless, he found himself standing in the middle of the lab, holding a large metal hoop and feeling very silly, with no idea how he'd been talked into doing this. Rodney was messing about with a remote control, trying various different combinations of buttons when the hoop had lit up and started vibrating. Carson dropped the thing as if he had been bitten and took several strides backwards. He was almost at the door when the thing kawooshed in the same manner as a Stargate establishing an active wormhole.

It had lain there in the middle of the floor, event horizon glittering like the surface of a swimming pool on a sunny day. Rodney had moved cautiously towards it to take some readings while Drs Simpson, Kusanagi and Zelenka tied a camera to a metal pole and fed it through to see if they could get a reading from the other side.

After half an hour, they had established that it didn't function like a Stargate, opening a wormhole to a different place. The film on the camera showed footage of the room in which the hoop device had been found, but when someone was sent to the room, there was no camera hanging in midair and they didn't appear on the camera's footage either.

Rodney finally deduced that the hoop was either a time travelling device, or it was meant to travel from one universe to another. The remote control was probably used to dial different combinations for different universes. It had taken both Carson and Dr Zelenka to hold him back once he had decided that someone should go through. Carson had picked the device up, hoping to find a way to turn it off, only to find himself unable to let go. It was as if his hand was physically stuck to the edge of the hoop and try as he might to drop it like a hot potato, his fingers wouldn't respond to the command to unclench.

-----xxXxx-----

"That was when it all went dark and I woke up to find myself being told off by that EMH fellow."

"I take it you don't have an emergency medical hologram in your universe?" Rodney mused, half talking to himself. The dog had somehow climbed up onto his desk and Rodney was scratching it behind the ears again.

"No… it's a hologram? It looked pretty real to me." Carson was still trying to keep up with all the differences between their universes. If Dr Lam was an android, he supposed there was no reason why Woolsey shouldn't be a hologram. He was half expecting Dr Weir to walk in saying "resistance is futile" and try to assimilate him.

"If you have met Mr Woolsey, I can see why you'd be surprised be the EMH's appearance," Atlantis said kindly. "It takes the form of whoever activates it, which in this case happened to be Mr Woolsey."

"Well, he certainly didn't activate any holograms while he was on my Atlantis," Carson replied. "I think I'd have noticed if he suddenly appeared in the middle of my infirmary and started to order me around."

"Wasn't he stuck on Atlantis when the Replicators took over?" Rodney asked. Every time Carson and the AI started to drift into conversation like this, he would start tapping his foot and checking his watch, but it seemed that this time he was interested in what Carson had to say.

"Aye, he and General O'Neill stayed behind with the Ancients when they took control of the city, then when the Replicators took over the two of them were trapped. The four of us – Dr Weir, Colonel Sheppard, you and I, as well as Teyla and Ronon, came back to rescue them and get rid of the Replicators."

Atlantis shivered a little, and Carson remembered that for all intents and purposes, she was the city. Having the Replicators use her for their own purposes couldn't have been pleasant, especially if she was separated from her friends and husband.

Rodney, however, seemed oblivious to the AI's discomfort. "Yes, that's pretty much what happened here, except Atlantis here obviously couldn't leave the city, so she was trapped here with Woolsey and O'Neill. And it was Jackson who came back with me, Elizabeth and the Colonel, because I've never met you before."

"And Woolsey activated this EMH thing, which now seems to be running the infirmary single handed," Carson added.

"Yes, well, it was kind of forceful in taking charge and it made the voodoo witch doctors we had look like chimps in lab coats, so they were recalled to Earth when it became obvious that they were completely redundant."

"Who was the CMO here in the first place, if it wasn't me?" Carson had wanted to ask this question for a while now, but hadn't yet found an opening.

Rodney was back to tapping his feet impatiently. "Does it really matter? It was Dr Keller, now can we look for the hoop thing, assuming it exists in this universe, and get you out of my lab and back to your own universe?"

He glared at Atlantis until she got the point. The AI's eyes started moving as if she was reading something that only she could see. "Searching Database."

Carson watched her for a while, then realised that nothing interesting was going to happen. "How long is this going to take?" he wondered.

Rodney was fussing over his dog again. "I thought I was the impatient one, here."

"I guess that means you have no idea." Carson found a stool under the nearest desk and sat down on it. "I never had you down as a dog person," he said as he stroked the dog's back gently. "In my universe, you used to have a cat."

"Really? I hate cats. They make me sneeze and my face swells up." Carson thought he detected a smile on Rodney's face as he ruffled the fur on his dog's forehead. "Mars is the only one who understands me."

"How did you persuade Stargate Command to let you bring a dog to another galaxy?" Carson asked. "Or did you smuggle him on board the Daedalus?"

Turning his attention away from Mars, Rodney looked up and frowned. "Hm. I keep forgetting that you're still at war with the Wraith in your universe."

"What's that supposed to mean?"

The look in Rodney's eyes could almost have been pity. "The Atlantis expedition is more like a settlement than an expedition, these days. With the help of the AI, we now have three fully charged ZPMs and almost three hundred scientists live in the city with their families. Sheppard and Teyla have settled down on the mainland, Ford and Ronon both have families now and I have…"

"You have Mars," Carson supplied when he saw the wistful look in Rodney's eyes. The news that Ford was still alive made him feel happy and guilty at the same time. After all, it was partly his fault that Ford had escaped the infirmary and left Atlantis in search of more of the Wraith enzyme.

"Yeah," Rodney agreed quietly. "I have Mars." He looked up and shrugged. "I asked Jeannie to come live on Atlantis, but she didn't want Madison to grow up in another galaxy. Personally, I blame her idiot husband. He probably persuaded her not to come."

Carson was about to say something comforting, but Atlantis chose that moment to complete her search of the Database.

"I've found the device," she told them. "It was catalogued along with the others when the area was cleared for habitation."

"Lead the way," Carson said, glad that he'd soon be home to his own Atlantis who didn't talk and look like a woman he'd once worked with. To an infirmary bustling with nurses and patients. To a Rodney McKay who knew who he was and didn't say 'best friend?' like it was an impossible concept, or 'lover?' in such a hopeful voice.

-----xxXxx-----

Everything was dark, but this was a familiar dark that held the voices of Rodney and Elizabeth and all of the nurses who were like sisters to him. Carson groaned and tried to wave a hand in front of his face, but found it caught in another warm hand that refused to let it go.

"He's awake! God Carson, don't scare us like that again! What did you think you were doing, grabbing hold of an active… whatever-it-is and disappearing into the event horizon?"

Finding himself able to open his eyes, Carson blinked up at the Rodney McKay currently holding his hand and decided that he was back in his own universe. It turned out that he was able to talk, too, because he found himself saying, "Might I remind you that you were the one about to jump through the bloody thing head first?"

Rodney had the sense to look sheepish for a second, before raising an eyebrow and launching into a denial of his actions. "He's delirious. Doesn't know what he's saying. Must have hit his head when he came back through, right Carson?"

"Right. Well, if I'm delirious I don't suppose you'll mind if I do this, then."

Pulling Rodney down to his level was easy enough because he still had hold of his hand and the scientist was caught by surprise. Kissing him was even easier, because the second Carson pressed their lips together, Rodney started kissing him back as if he'd just discovered the meaning of life, the universe and everything.

And Carson knew that there was much, much more out there than that, but he really didn't care when Rodney was grinning at him like a fool and swooping back down for another kiss.

Maybe when they finally defeated the Wraith, Carson would get a cat and call it Mars and he'd never tell Rodney the reason why.

A/N: I don't know whether I should explain this, but not everyone is as big a nerd as me. OK, so the actor who plays Woolsey (that IOA guy) also plays the EMH in Star Trek: Voyager, the sexy lady who plays Dr Lam in Stargate: SG1 is also Andromeda in... uh, Andromeda. And Mars is David Hewlett's (the actor who plays Rodney) dog, and he has a starring role in Hewlett's new film, A Dog's Breakfast.

Now, to quote Rodney: Go away and be stupid somewhere else. Or give me feedback... smiles hopefully