I own her
People do a lot of forbidden things they would never admit, even though they find them fulfilling or even amazing. And I think that must be a pretty frustrating experience. I, for one, am pretty open about the fact that my older sister and I have amazing sex. We've been sex partners for about five years, and fucking together has never been anything less than incredible.
She's 10 years older than me (I'm curently 27), and she's always been very open-minded, sexually speaking, very willing to explore taboos. Once I reached adulthood, she started to be occasionally flirty with me, and even admitted being attracted to me. I didn't act on it at the time, but one night, drunk after a family dinner, we ended up fucking. We've been hooked on each other ever since.
It turns me on how much she enjoys anal. Both of us have multiple sexual partners, but she says I own her because I'm the only one allowed to pump her ass full of cum. She has an intense cum fetish, so she climaxes every time I do. Any other man that fucks her in the ass must do so with a condom, except me. I also get to cum inside her pussy, but only on safe days.
But my wildest fantasy is to do so any day I like, to pump her full until she becomes pregnant with her one brother's child. And I wish we'd tell people we're siblings who fuck deliciously and are expecting.