Call yourself a mother? (would also consider Step Mother)
A curvacious mother living with her only 18 year old son, the father long gone with a younger woman. The boy is getting in to masturbation and looking at porn, unknown to his mother until she comes across one of his magazines stuffed under his bed, smiling to herself as she shakes her head, knowing the urges he must be going through she decides to surprise him with some new magazines and maybe a video, sitting him down and letting him know that it is ok and it all apart of growing in to a man.
Feeling more and more interested in her son's behavior she starts to wear more revealing clothes at home showing off her figure in hope he catches sight of her and takes notice, feeling the attraction inside as he does start to notice, his eye's looking at her every now and then with a glint in his eye, until one day the inevitable happens.
This will start as the mother being the seductive one and then he will turn her in to his sex slave as he grows dominant with her, trying out all the things he wants to do with her.
This is open to anyone who wants to play the character of the mother :) (male or female it does not matter)