Author's note: Despite the title, this is NOT a blood-incest story. I only write pretty vanilla stuff. The title popped into my head when I was thinking about the ending.
I'm putting this in the humor and satire category because, interspersed with a few titillating scenes, the story revolves around a minimally sexy act of sex, and inverts a lot of tropes like cheating, three-ways, non-blood incest, and so forth. I had started it intending to follow the trope of "dykes discover dicks" but decided that was a little disrespectful, and I had to consider the characters and their motivations - it just wasn't going to work as plain erotica and was much easier to write this way.
Also, all discussion of reproductive biology is as made-up as the sex, so, duh, please don't be mean to me, especially if your initials happen to be EC and you make brownies that give me a mouthgasm.
We were reading in bed, quietly, when my wife turned to me. "Jack, honey, I have a pretty big favor to ask of you."
I nodded my willingness. "Sure, love, anything you need."
"I need you to fuck my sister."
Those were not words I ever expected her to say. For one thing, I only fuck my gorgeous wife Margo, and haven't dallied with anyone else, nor wanted to, since before we met. For another thing, her sister Elspeth is happily married - to another woman.
"What?"
"Elspeth and I were talking about her desire to have a family with Anne. They had been discussing whether to use a sperm bank, have an anonymous hookup with a random(ish) man, and hope it worked out, or to try to choose a particular donor."
"Let me guess..."
"It was actually Anne's idea. She loves our kids, Elspeth's nephews, and that put the bug in her bonnet."
"Wait, so my sister-in-law's butch lesbian wife got baby fever seeing Miles and Felix, and now you
need
me to raw-dog your sister?" I did an imitation of that blowhard cartoon chicken, Foghorn Leghorn.
"That, my dear, is preposterous."
"That's not preposterous enough. You also have to raw-dog Anne."
Anne could have been on the cover of a fashion magazine called
Bull Dykes In Flannel
. She drove a Subaru, had very short hair, baggy jeans, Doc Martens, all the body hair Nature gave her, and enough piercings that she had to be very careful to remove them all before trying to go through airport security. Underneath that tough-looking exterior was a physique toned by daily workouts, and gifted by Nature with a shape that was unmistakably female.
On the surface, you'd never think of Anne as being the slightest bit interested in motherhood. But the style she adopted was just her way of being flagrantly out. She was also a warm, funny, and nurturing person who actually, now that the thought was allowed to enter the realm of possibility, would probably be a pretty good mom.
"Also?"
"They both want the experience of pregnancy. I understand -- it's a powerful, powerful urge. And I know you used to find my sister attractive."
That's true. I had been introduced to Margo after three really fun outings I had considered to be "dates" with Elspeth. Those put us in a good friend-zone relationship, and Elspeth, after the third no-that-wasn't-a-date, came out to me, telling me "That's why I never considered these as dates -- the thought literally didn't enter my mind." She hugged me, and said she thought her big sister might like to meet me.
Six years later, Margo and I had a toddler and a preschooler, and Elspeth needed a sperm donor.
"I am going to have to think about this."
"You know I wouldn't consider it being unfaithful."
"I know. And I need to process that myself, and ... wow. I mean, it is a lot to consider."
"I know, honey. And we can talk it over a lot, between ourselves and with them." Margo reached down and fondled me through my pajamas. "Right now,
I
need a sperm donor." She'd had a surgical sterilization along with the C-section that gave us Felix, and I was more than happy to send my sperm on a futile quest to her dead-end Fallopian tubes.
In the morning, I had done some thinking. "I guess I could be a sperm donor for them. If I trusted anybody to raise my offspring other than you, it would be those two." I winked at her. "Especially if you help with the collection process."
"That's the hard part. They don't want to do artificial insemination. I don't understand it either, but they have persuaded themselves they want to start their babies the old-fashioned way, not even the turkey baster method."
We were definitely going to have to do a lot of talking to work this out.
"I guess we should start by having them over to dinner, this is going to need group thinking. Not just technical infidelity, but possible emotional consequences, legal paternity, so many issues."