Also could even be like normal forced sex on son plus pegging sometimes.
At which point it kinda just devolves to femdom (
probably), motherly or gentle femdom i've seen listed before.
I remember finding one of forced milking on literotica; It suggested it was a measure keep her son from being able to get a girl pregnant and less free-use; But read more like semi-rape.
Another one, not exactly free-use, a story called 'the darkroom'. It was about a camera/photography club (
think 70/80's and earlier) where they had to do everything in the dark or risk exposing the film; The 5 girls (
one of which was his own daughter) decided they'd ask for help in complete darkness and get felt up, give a blowjob, or hankypanky to some degree, and he wouldn't know who it was.
I wonder at what point that the erotic goals are too easy. Stories generally need some form of progression or obstacle; It doesn't have to be big, but automatic no-effort success is...... boring.... I mean if you gotta rub one out right away that's fine, like starting in the middle of a porno. A lot of the eroticness often is the tension and buildup, and far less the final act of getting one's jolly's off.
Maybe that's the kink here
Maybe. Most males would likely be more than willing to go along with it. I mean religious types or those with a disdain probably not, but those aren't the types you'd write/read for anyways. But girls (
other than sluts) would be a bit more resistant to it.
But yeah, can't think of that many.
Otherwise i suppose open relationship, rape or dub-con... Ignoring / pretending... Maybe reverse free-use? (I
've seen 'reverse' used a lot on n-hentai and tags, it just changes who is the target/sub)