AN – Written simply because Stark's obsession reminds me of Rodney's. Somehow this changed into a past slash when I wasn't looking.

Summary – Stark's obsession in Sector Five is about to overload. He's still convinced he can fix it, but sometimes all you need is someone who understands… Eureka/SGA, Past Stark/McKay slash

Rating – PG-13

Disclaimer – I don't own Eureka or Stargate

Simple Understanding

Carter pinched the bridge of his nose. "We need to evacuate Eureka, in case-"

There was a snort behind him. "Oh, like that's going to do any good."

He turned, surprised by the look of wary relief on Alison's face.

"What do you mean?"

The new man gave him a sour look. "I mean that if this thing blows it'll take out the planet, forget Eureka."

"Rodney, glad you could make it." Alison smiled forcedly and the man, Rodney, smirked tiredly.

"Yeah, well, let's just say I understand."

She nodded. "I'll call the President, tell him that you're here."

"Rodney," drawled a man in the doorway. "I can understand how you want to play catch-up but could we please get this show on the road."

Rodney nodded, his face tight. "Right, but can someone please tell me when it was decided that I should get to play Xander to his Willow. There were no yellow crayons in our past, let me assure you."

"Rodney."

"And my radiation exposure levels are-"

"Rodney!"

"Right. What's a little radiation poisoning between friends?" Rodney took a deep breath and stepped towards the door. "Nathan?" he called tentatively. "It's Rodney McKay."

There was a couple of seconds and then the door slid open. Rodney winced and then stepped through it. The man made to go with him but Carter's hand on his arm stopped him.

"Why aren't we going in there?" the man demanded as the door slid shut behind the scientist.

Carter watched the other man curiously and introduced himself.

"Jack Carter, Sheriff of Eureka and we're out here because Stark respectfully requested that we stay outside."

The man smiled tiredly, the type of expression that suggested that existing on the brink of annihilation was a normal day. "Naturally, when obsessive, suicidal, homicidal geniuses 'request' that I stay outside I do too. Lieutenant Colonel John Sheppard, USAF. Nothing to do with Eureka, just along for the ride."

Carter nodded at the door. "And him?"

"Doctor Rodney McKay, former resident of Eureka. Smartest man in the world and from what I've heard about this town that is saying something."

He must have looked doubtful because John snorted. "Yeah, I didn't believe it when he first told me either."

"What did he mean when he said he understands?"

John looked tired. "That would be classified and if it weren't for the fact that the world is probably going to be gone soon I would worry that he'd told you that much. Can't we see what's happening in there?"

He shook his head, startled by the suddenly emotive display, it was surprising how calm you could be when the fate of existence was in jeopardy. "That was the first thing Stark disabled."

"Of course it was." The man ran a hand through his hair. "Look, screw this."

He pulled something out of his pocket. Carter didn't recognise it but that wasn't anything new for this town.

"Hi, this is Sheppard. I need a visual for inside that horrible, long, ominous looking corridor my chief scientist just disappeared into and I need it now."

A couple of seconds went by and then a grainy shot of the corridor appeared. John sighed in relief. "Thanks Hermiod."

There was silence for a few seconds while Rodney paced emotively and waved his hands dramatically before John spoke again. "Audio would be nice."

There was a grumbling on the other end of the line and then Rodney's voice came through the room, sounding tinny.

"Look, Nathan, I know that you must really not want to speak to me right now but you have to stop this."

They couldn't hear Stark's response but apparently Rodney could because he paused, listening to the answer.

"Because it doesn't work!" Rodney sounded slightly desperate now. "I tried it myself. I got like you, obsessed. I needed someone to drag me back from the edge and he did but I nearly got us both killed and I destroyed a solar system. That one was uninhabited but this one isn't. There are over six billion people on this planet and four ships in range if that thing blows."

There was another silence and Rodney chuckled coldly. "Yeah, I said that too. Professional jealousy. I should have listened to him and I had no where near as many reasons to mistrust him as you have me but this isn't about revenge or stopping you from making a discovery that should be yours. I can see the levels out here too, we haven't got much longer."

Nathan said something again and Rodney broke, screaming at him this time. "Look, will you get it through your thick skull that this has nothing to do with me and you. You left me for Alison Blake and a ready-made family. I get it, I got over it. You're not the first person I've been with who's left me for politics." Behind him Carter felt Alison flinch.

Rodney continued frantically, "this is about that fact that you'll kill every single person on this planet if you don't stop now. I waited too long, I couldn't stop the overload and I destroyed everything within about three billion miles. Do you know what that means for here? Towns, cities, countries… Mothers, fathers, children, brothers, sisters… Everything, just gone. So if you ever trusted me, ever, you'll stop this now." His eyes were wild. "Nathan, please!"

There was silence and then Rodney's body sagged and the door he was standing next to opened.

Nathan Stark dropped to his knees beside the physicist and buried his face in his shoulder. Rodney wrapped a hand round his shoulders tightly, squeezing his eyes shut.

Alison exhaled slowly from behind him and he realised she'd been holding her breath. She wasn't the only one as John sighed in relief next to him and sagged against the wall.

"I'm sorry." A voice Carter didn't recognise cracked out the words.

"I know," Rodney murmured, running a hand over Stark's head. "I know, it's okay. You can come with me for a bit, get a break from this. It'll be fun, we exist on the verge of constant disaster and get held hostage by technically inferior natives once a week, you'll love it."

"I'll call the President," Alison muttered after a second. "Let him know that… everything's okay."

Carter waited until she left the room and then turned to John. "What should we do with that thing?"

John turned weary eyes on him. "Destroy it and then destroy the pieces. Rodney was right, it doesn't work and the thought of it has a tendency to corrupt."

Carter nodded and then asked the question they both knew was coming. "Did he really destroy a solar system?"

John laughed. "You aren't supposed to know about that but yeah, he did."

Carter nodded and decided to deal with that later. "Is Stark going with you?"

John hesitated and then nodded. "Yeah, probably. It'll be a good idea to get him out of here while it's being dismantled just in case he gets…" He shook his head but didn't finish. "Besides, from what I've heard it'll be good for him to be a scientist again, one who has to think on his feet constantly, rather than about the political nonsense." He grinned. "That's what Elizabeth's for."

Carter nodded, he may not know who 'Elizabeth' was but he understood the concept perfectly. Let Stark play the role of the scientist for once, it would be good for him. Especially since it sounded like he was going to have to answer to someone else.

Suddenly the two men in the corridor disappeared in a beam of light and his eyes popped. "What the hell…"

John turned too and then smiled. "That's my lift. Nice to meet you Sheriff, I have the feeling this isn't the last time we'll see each other. Granted we'll probably next meet when the world's in peril… again, but from what I hear that's business as usual around here."

Then he gave the Vulcan salute and disappeared, the words 'beam me up, Hermy' ringing round the room.