Warning: Non-graphic incest.

Setting: Pre-movie, post accident

Originally posted on contraparrhesia

They were sixteen when John was faced with the cold, hard truth about his relationship with Sam: They weren't at all normal siblings.

He'd never given much thought to it before, mostly because no one had. Olduvai's sense of normalcy was exactly what he and Sam encompassed--they were brilliant children who thought studying was fun. They largely kept out of the way of the adults, helped out on the safer grunt work that piled up, and got along with the other children with the same borderline apathy that the adults treated each other with.

When they got down to Earth in order to start college, their worldview was shaken in ways they hadn't expected. They'd been told they'd be young for what they were doing, that most kids didn't graduate high school (or the pseudo-home schooled equivalent they got) when they were thirteen. And most of the older kids still had at least one living parent around who was supporting them, not a corporation with a vested interest in their futures.

The two of them pushed that aside, though, treating it all like a new find at the dig. After a day filled with more classes than they were technically allowed to take, the two of them would lie down on the carpet in front of their couch, talking about their days as if dictating ethnographies. It kept them going for the first few years, helped them to ignore the looks and whispers, the fact that everyone wanted to partner with them for projects but no one bothered to sit with them at lunch. They were children of Olduvai, those stuck on Earth could never understand what that encompassed.

John was the first to make a friend, a football player he was tutoring in Cosmic Evolution. He'd taken John under his wing, teaching him all the sports John had only ever heard mentioned in passing and praising his talent, his physical prowess. Back on Olduvai, they kept in shape simply because there was physical work to be done, but John had never realized how accomplished he would feel just by winning a pick-up game of football or an intramural ultimate Frisbee tournament. Without noticing it, he suddenly had something he couldn't share with Sam.

And it was through his friends, Adam the football player, Maha the art student, Felix the Environmental Science major, that John started to realize that maybe it wasn't Earth that was the problem, maybe it was Olduvai.

Which brought him back to the fact that he and Sam weren't normal siblings. It would have been bad enough if they'd been born on Earth--she was the eldest, but only by two minutes, he was the brother, but not the "big" brother. There might have been conflicting rules, she might have tried to baby him, he might have been overprotective of her. The longer they stayed on Earth, the closer to true that became.

There was also the very real fact that they were too close. Space was a premium in Olduvai, which meant Sam and John had spent their entire lives sharing one bed, cuddled up together against the chilled night and even through the oppressively hot days. Their breathing always fell into the same rhythm, their heartbeats, too, when they counted them, pressing their hands against each other's chests. They knew what every little sound they made meant, what emotion was behind every expression.

Or, at least, they did. When their parents died, they'd clung to each other because there was no one else for them, but something had changed. There were cracks running through them, ones they hid with the oddities of Earth and college, but that grew nonetheless. That grew until they were broken.

It started with alcohol. John drank when he went out with friends, but Sam never had. She didn't know when to stop, came back one night repeating the words "I'm so drunk" as she walked towards John. He'd expected her to collapse at his side, maybe cuddle up just before passing out. He'd even worried she might throw up on him.

Instead she'd sat on his lap, leaned forward, and caught his lips in hers. It was their first kiss, a part of John acknowledged it was right that they were sharing it, but it felt too good. He'd gotten half-hard just from it. Her hands had roamed through his hair, tugging at the locks, then flowed over his neck, pressing over pressure points.

He'd come in his pants with his sister humping against him, faced with the irony that if they'd never left Olduvai, he would have never known it was wrong.

The next day he quizzed Adam on his father, whose adventures in the military had always filled John with a certain wanderlust. Adam, with a fond expression on his face, had grabbed John's PDA and typed the address to the nearest recruitment center into his GPS. "Have fun," he'd said, as if he truly believed John would.

The exhaustion from training, the sound of rail and machine guns, the vibrating of the tanks going by, all formed into a barrage that kept the past--and things best left within it--from his mind. It had only taken a few months for John to realize that fun was exactly what it was.