Hers

Carrie nods in affirmation as if you’ve asked her to do something within reason.

“You’re okay with this?” You ask, pulling a pair of boxers on.

“I told you I would be.” Your girlfriend (your actual girlfriend) says.

And you can’t believe it “it’s just that... I mean you’re acting like I’ve asked you to do a normal thing. You sure you never....”

“No, I told you. I never fucked my own sister” Carrie responds with a nudge “but I’m honored that you think I’m naughty enough that I might have.”

And now a moment to introduce Carrie’s sister Cassidy. At 21 years old, she’s 4 years younger than Carrie and really does look like a slightly younger version of the same girl, maybe a little lankier, and surely more innocent, though you can’t say you know her that well. You only met her once when her family came to visit for 4th of July.

Carrie’s family lives out of state, but not too far, just the next state over. Her sister still lives at home and goes to community college. You doubt that she’s as perverted as Carrie. After all of she still lives at home, how could she even manage it.

But Carrie doesn’t seem to think this will be too hard to pull off.

“So here’s what you do. Tell her that I’m insisting on having an open relationship and you’re exploring side pieces. So if she’s ever in town you’d love to hook up. Meanwhile I’ll invite her to come visit me for a weekend.” Carrie wags her eyebrows.

“You think that’ll really work?”

“Sure. She’s 21 and looking for some adventure and independence.” She notices you’re feeling dubious “if you can get her to send you a naked pic, it’s over. She’s ours”