Cause and Effect

by Jessa

Spoilers: Anything's fair game through Season 8

Disclaimer: I don't own them; I'm just taking them out for some fun. I'll put them back when I'm done. Promise.

Summary: Jack takes a little trip, meddles with cause and effect, and thoroughly confuses himself along the way.

SamJack, of course.

Prologue

It was one of those rare, quiet days around the SGC. For once, Jack wasn't seeing to any particular crisis - all the normal, daily business stuff occurred without incident, right down to the three hundred and seventy-five boxes of Bic pens that arrived on time thankfully staving off the panic that would unfold if no one had any pens. Jack had actually been concerned for a while there, for fear he'd have to reveal the supposedly secret stash of pens that Daniel had been accruing for years. Of course, if Daniel were to share his stash, Jack was fairly certain they'd have enough pens to last for the next fifty years.

Free of the easily avoided pen shortage, Jack spent the day in his office, absolutely not working on any of the million pieces of paperwork he needed to work on. He saw no point in ruining such a perfectly relaxing day with paperwork that was bound to frustrate him.

An hour or so after lunch, Jack grew tired of staring at the walls in his office. Fearing such a thought would prompt the universe to do something to mess up his day, he decided to go for a walk. Naturally, he wound up in the doorway to Carter's lab. Daniel was already there, as he usually was whenever Jack found himself inexplicably drawn to that room. Teal'c had obviously just arrived and was making himself comfortable on the stool next to Carter's. His three friends looked up simultaneously and smiled. It was times like that when he wondered if Urgo had really been removed from their brains or if he had simply chosen to hide except for those random times when all four of them had the same thought at the same time.

Or maybe they had really just spent far too much time together.

Of course, he thought to himself as he returned the smile Carter offered him, it was physically impossible to spend too much time with her.

Daniel was usually the one to start the conversation because he was always the one who had at least a dozen philosophical conversation topics at the ready. Jack was fairly certain he wrote them on index cards and had them organized in a little card file so that he would never be at a loss for words. His topic that day was fate - how things had worked out the way they had, if that was the way they were supposed to, if things were predetermined or if people had the power to affect things on the grander scale.

Jack leaned on the counter a few feet behind Carter, content to just listen for a while. Jack knew Carter would immediately dismiss the idea of fate. She'd quote some law of physics from some obscure scientist that would shatter Daniel's theory. Daniel and Carter would argue it for twenty or so minutes, intriguing Teal'c and confusing Jack, until the conversation became heated. Then Teal'c would jump in with something that no one would be sure was serious. Jack would follow that up with something seemingly idiotic that Carter would undoubtedly attribute to some brilliant flash of insight. Then pretty much everyone would agree that something someone else had said was at least partially accurate. That would be Jack's cue to bring up dessert and they'd all head off for Jell-o and pie.

Yes, he had the whole thing planned out in the amount of time it took Daniel to finish his original thought.

But that time was different. Instead of ranting about molecules and atoms and energy and uncertainty, Carter smiled enigmatically and said she was fairly certain things happened exactly the way they were supposed to.

Jack wasn't the only one who was surprised. The three men stared blankly at Carter, trying to figure out what to say. They all thought they knew her better than that.

Daniel was the first to recover, putting forth the versions of her in the alternate realities. They hadn't joined the military, he said, so did that mean she wasn't supposed to join the military either. Carter didn't hesitate before pointing out that obviously not joining the military had been how their realities were supposed to go. Teal'c jumped in unexpectedly, asking it that meant she too was supposed to be married to Jack. Jack squirmed uncomfortably, feeling the embarrassment that Carter refused to show. She repeated her statement, claiming that was the way it was supposed to go for them.

The thought came to Jack quicker than he would have expected, especially since it wasn't a flippant remark designed to make everyone think he wasn't paying attention. "So then we were supposed to find the time machine, go back and change history, and then make it so we didn't have to go back in time and change history?"

Teal'c and Daniel stared in disbelief at Jack for having asked a serious question. Carter twisted slightly to face him. "If you go back in time and change something, who's to say that it wasn't meant to be changed?"

He crossed his arms over his chest, content that he'd finally succeeded in getting her to contradict herself. "But I thought we weren't supposed to change things. Whatever happened to preserving the timeline?"

Rather than bumble through some scientific explanation that was meant to hide the fact that she was mistaken, she grinned like she'd planned the whole thing. "What ifthe act of changing something is preserving the timeline, in and of itself?"

The room fell silent for a moment until Daniel cleared his throat. "So, cake, anyone?" Teal'c nodded and led the way to the commissary.

The group only made it as far as the elevator before Daniel started in on Carter and why destiny should have different ideas for her in different realities. He once again held up the example of her military career, which seemed so innate to her and had seemed repugnant to the other versions of her.

Carter was much calmer than she usually was when she was being challenged and Jack wondered to himself if that was because she thought she was meant to be challenged. She shrugged. "I think those other timelines were aberrations. Mistakes, really. Think about it, those two realities we encountered were basically this one, but horribly wrong. Millions of people were dead. Teal'c served Apophis. You never joined the program. Most of the people we know, including ourselves, died. It's obvious that this reality is the way it was supposed to go."

Daniel shook his head emphatically. "But this reality was wrong to them."

Carter grinned. "And now they're dead. Proves my point rather effectively."

Jack chuckled to himself and rejoined the conversation as the heckler he normally was. "Screw with fate and die!"

Daniel glared. Teal'c smiled. Carter giggled. "Exactly, sir."

Daniel was growing frustrated with Carter because she was uncharacteristically arguing without any sort of proof whatsoever. "But that doesn't make any sense. If things are destined to happen, why don't they always happen the same way? Why didn't we all die anyway? Why did you join the military?"

The elevator doors had opened, but the group hadn't gotten more than a few feet beyond them. Carter turned around and smiled happily at Daniel. The gleam in her eyes made it clear that she was going to decisively win the argument. "Because this timeline was changed." She had the unwavering attention of her friends and she turned away with renewed interest in Jell-O.

Daniel turned to Jack. "How does she know?"

Jack shrugged. "The fish?"

Teal'c contemplated Carter's back as she walked away. "She does seem quite convinced that what she's saying is correct."

Jack started down the hallway behind her. "Doesn't she always?" In his experience, it was a rare occasion that Carter wasn't absolutely committed to what she was claiming.

"Indeed, O'Neill, however I believe this time it is different."

Daniel nodded. "I think you're right, Teal'c." He practically ran down the hall to catch up with Carter, insisting that she explain herself.

She resisted his barrage of inquiries as she ate. It was as she scraped the last remnants of Jell-O from the bottom of the dish that she finally looked back at him. There was no gleam of impending victory, only a content smile. "Because I remember something that hasn't happened yet. And that something made the difference between this reality and those other ones."

That time when Carter walked away, the guys were all too dumbfounded to follow her.