This idea is still a little vague for me. Really depends on who is interested since i see many possibilities floating around with it.
There is really potential for this to be a small group (3-some) game. I'll try and explain it as best i can. It continues to develop even as i write this.
Setting: Medieval or Fantasy
Idea(s): The King is dead. His 20 year old son, the Crown Prince, moves swiftly to quell any sort of usurpation of the throne by those who feel they deserve it. But his position is unstable, the thrown to his right remains empty, no Queen to claim it. The Council have decided that the Prince-King need to marry and soon. But he is used to a life of revelry, taking after his father who sired more then one bastard-child. There are several hopefuls who live in the castle or capital city, but can they do enough to turn his attention away from the chamber maids and become the next Queen?
Alternate Idea 1: The King and Queen rarely speak to each other. The King takes serving girls and chamber maids to his bed on a nightly basis, further pushing them apart. They eye of a Noble woman has caught his eye and though he knows it is improper to pursue such things, he lusts after her. Does she lust after him.
(Alternate to this is that she is also married and steals away to the Castle for a Royal Affair with the King.)
Incest (kinda) Idea: The King and Prince both lust after the same woman, who is not sure which card to play when dealing with the two: the King being married, and the Prince being several years younger. But she enjoys the company and attention of both: how long until they find out about each other?
(Alternate: The King remarries, but little does he know his new Queen is sleeping with the Prince behind his back. Not only that, but she enjoys gangbangs carried out by the Prince and his Inner-Circle friends. Will he be enraged when he founds out, or will he want to join in?)
Like i said, many ways all of these ideas could go, especially based on character personalities etc. If you're interested, please let me know!