One idea I have that keeps bouncing in my head involves a woman, in late 30s, early 40s, who was recently divorced and has sole custody of her young daughter, I think 16 or 17 on that one.
Now this can take a few directions but I see it going two ways mostly...
One is that the daughter is bitter about the divorce and has starting acting out, only to be caught up by the wrong older man who has broken her sexually and made her his devoted toy... she has come to love the way he uses and abuses her... and now that he has set his sites on her mother as well she is going to help him get what he wants...
Or perhaps mom has just started dating again, met a man whom she is immensely interested in, only for that man to string her along while setting eyes on her daughter as well... maybe the daughter has been teasing him or maybe he just presses her against a wall while her mom is at work...
Of course if the Inc isn't your thing then an idea sticks in my head about two room mates, one adventurous and liberated while the other is introverted and quiet. Now they have been friends for a while but the more adventurous of the two is tired of her friend judging her... so she sets her up with a self described aggressive and dominant man, intending to give her a bit of a shock.
What she doesn't know is that this man is a sadist, who intends to completely break the innocent girl and then have his way with the more adventurous one...
The ideas are open, I want a small group for this going, me and two others though if one other person can handle both roles then that is fantastic. If you have an idea along the same lines then let me know and we can set this up, explore an interesting story with a few people.