This one is basically a pair of teenage twins, a boy and a girl. The boy has always been quiet, shy, and mild, and a little nerdy. The girl, on the other hand, is confident, outgoing, and aggressive, though she can keep up with her brother in academics, too. They're extremely close, and there's always been an unspoken attraction between the two of them, but neither of them have ever acted on it. For her part, she's had lots of boyfriends. He only has had one, though, and though he frequently comes home with hickies, his girlfriend never seems to have one. The sister, naturally, teases her brother about it until he explains that while he's tried, he's always too gentle with his girlfriend, afraid to hurt her... so the sister offers to let him practice on her, and things spiral out of control from there. I imagine that, when it finally got to the sexual part, she'd be more naturally dominant, and he more naturally submissive, but they'd both ultimately be switches as she tries to teach him how to be more dominant, though sometimes she'd dominate him just because she feels like it. D/s expected, bondage and other kinks open for discussion, but by no means required. Could be a one-shot, or an on-going story.