This goes through a few changes, and is more than one story. Not sure if anyone will like the first part, but if you can power through it, there is other stuff.
Everyone portrayed in this story is over 18, at least when it matters. Some of them are almost painfully older than that (though they may not act it).
A Beautiful Sibling Story.
He was 16. His sister was 17. But they never thought of each other that way. Which was good, because they were both too young.
She was sad. Her boyfriend was mean. Her brother cheered her up. She would forget about this until later, when it suddenly meant everything.
He was n. His sister was n+1. Both were finally over 18. By how much, we can only guess. Time is defined by how we choose to quantize it. They were most likely farther past 18 than the entire lifespan of a fruit fly. He was, that is. The one that matters.
He was sad. He didn't have a date. She said she'd be his date. He was embarrassed, but happier. There lived in a country where they could have got married and fornicated in the middle of the street and no one would care. Hell no one would have even cared about their age. But this site does, so be cool. Anyway it didn't matter, because they didn't think of each other that way.
They were back home on the couch watching TV. There was also exercise equipment close by, just in case.
He noticed her bazoooooooooms. He tried not to look. She'd accidentally dropped a quarter on the seat cushion he was sitting on, and it rolled under him. She was going after it like she was noodling for catfish. He was suddenly thinking about her that way. Many ways. Any possible way. She had no idea.
She found her quarter. She also came back with a bottle cap, and the remote to an old TV they didn't even have any more. It's not a plot point. It won't come up later.
He thought about her a lot. Their parents had to replace the carpet in his room with grouted tile with a hose and a big drain in the middle of the floor. It was simply easier that way.
She went off to college to major in art history. He was a star athlete. Or maybe he wasn't because he was homeschooled and had never been on any actual sports teams. He took tests and went to a nice, but slightly less prestigious college than her. His major was business, but his heart was really into thoughts of pounding his sister like he was driving in the corner post of a fence that would have to keep dinosaurs in.
He dropped out of college to get married. He would stay home and raise the kids. Oh wait... No, that was her. He got a business degree and started his own shop selling older TV's to people who still had remotes to their previous TV's and missed them. I lied to you about the plot point. Sucker.
His business was shockingly good. He got rich. She didn't like her marriage. Her husband was a jerk, and hated her bottle cap collection. Got ya twice.
She got divorced when she caught her husband cheating on her with the next door neighbor, his wife, their legally of age son and daughter, grandparents, the uncle that they rarely talked about, and his wife who was born a man but was in the middle of a sexual reassignment program. There was a plumber there too, but he wasn't involved. He was just fixing the drain in the sink. He was ugly anyway.
She got everything in the divorce except for the kids. They thought dad would be a hell of a lot more fun in the future. She was too beautiful to be able to find another person to share her life with. She was lonely and sad. People felt bad for her because the rich have it so hard.
He had sold his business to a competitor. Yes, there could be more than one place that did that. Don't be closed-minded. He became richer, but sad because he still wanted her. No other woman would do but he still tried to get over her. He paid many women to help him get over her. It never worked, but he kept trying. Sometimes he tried doubly hard to get over her, so he had two women at once.
He got a cabin on the beach next to a forest where it snowed and a river met the sea. It was close to every kind of recreation known to man but he didn't want to be around people anymore. Of course he had a sweet internet connection. He wasn't insane, just sad. He watched lots of porn and made sure he stayed hydrated.
Their parents both died. Mother had gone off course in a training run for the Senior Olympic luge team, and and landed in the grandstands on their father. He was sitting next to a case of fireworks which exploded when a steel runner sparked against the plate in his head. All that could be found of them were her goggles and a giant foam finger.
Because of their combined life insurance policy, both kids were rich. I mean, they were already rich, but now they didn't have to work. Well, they already didn't work, but now they
really
didn't have to work. Fuck it. They had money.
They met in Innsbruck, Austria for the funeral. It was sad. Some of it was happy. There was lots of really really good beer. They couldn't believe how much they had changed, and yet, they were still the opposite sex from each other. She had become rich and beautiful, instead of just beautiful. He was also rich and handsome, instead of just horny all the time. She complimented him on his big sausage. He showed her where they were in the serving line and she got one too.
Their mother's wish was to be cremated and have her children spread her ashes about while going down a luge course. They said, "Fuck that," and reasoned that mom just didn't want anyone left alive after she died. Their father wanted everyone to drink a lot and love each other. They liked his wishes more.
They went skiing. When they got to the bottom, she was sad because she had been dragging her pet chihuahua around through foot-deep snow and it froze solid. He suggested that she could go buy another one and it cheered her up. She remembered how he once cheered her up before, earlier in the story, and knew that he was the love of her life.
She sent her chihuahua to a cryogenic freezing service, so that one day, science could revive it when they found a cure for her idiocy. She forgot to ship it in ice, and it thawed out and got all yucky. They didn't tell her and froze it anyway, keeping the money. Whatever. Science can fix that too.
They met their half Austrian/Australian grandmother for the first time. She told them the secret of how their parents were really brother and sister. They needed to be careful because the chance of birth defects was alarmingly high if they tried to have kids. They denied any kind of mischief with each other, but the grandmother suspected something was up as they stood before her with their hands down each others pants. The grandmother also warned them that they were probably themselves retarded, but they said "Nuh uh," and "No way," assuaging her fears.
The funeral/luge fest ended. They shared a cab back to the hotel. The hotel said they made a mistake in the bookings, and they would have to stay together in the converted rec room and sleep on the ping pong table. They felt embarrassed for the concierge not to call it a "table tennis" table as any adult should, but figured that he didn't want to sound redundant. They took the room.
Once in the room. They played a game of table tennis. He had the only paddle and skunked her soundly. She was enthralled by his physical prowess. He was truly the one for her. She was going to show him what she could do with one of the balls, but South Park already covered that and ruined it for the rest of the writers in the world forever.
They stripped down to their underwear for bed. Once they saw each other, they tried to think of clever, innocuous ways to get more intimate. He suggested a back rub. She yanked down his shorts and sucked him off. After that, they felt they may be getting close to each other in ways that society might not approve of. They weren't really sure, so they decided to fuck on it and see if the world ended tomorrow.
They made love like two people who had made love many times to other people, but never with each other, which was really just a lot of the same stuff but with different complaints. It was magical.
She was tighter than tight. Like, if Gigantor had a vagina, that's how tight she was. He would never fit. He had to work his way up to match his immense girth. After using his fingers, he pushed in.
"Oh my god," she exclaimed, "That's a monster!"
"No, it's a Red Bull," he replied, "they didn't have any Monster." Then he switch to his own massive member. It was huge. Not the biggest in the world, just bigger than yours or mine. Otherwise their sex would have been horrible. He went to work, huffing and puffing like he was trying to snake a badly clogged drain.
She couldn't believe how full she felt. She never felt anything like it, except for that one guy at the truck stop, but he didn't called her back so to hell with him. She didn't know that he wanted to call but got into a wreck and died or he would have called. He thought they were meant to be. Sadly, he was also her first cousin but they didn't know that. Actually, most of the people she ever met in her life were related in one way or another.