So I have had some really fun and bizarre and messed up ideas in the past, but even I think that this one is a little extreme. What I am primarily looking to explore here, is psychological torture and forced codependency, for reasons that elude me, both of those things are definitely on my ON list at the moment.
NOTE: In the description below I use female characters for parsimony's sake, but in practice am open to any combination of sex/genders.The victim has just graduated high school and will be moving away to college in the fall. She is incredibly bright and has a wonderful future in store for her. Her father died several years back and she is currently living with her mother. Unfortunately, her mother essentially has a mental breakdown over the prospect of letting her only child move away and takes drastic measures to reduce the victim from a functional young woman to a helpless child completely dependent on mommy.
The precise methodology employed will be up to the player playing the parent, though I would favor things starting subtly and slowly intensifying (e.g. the victim's mother drugs her meals to cause her to lose bladder or bowel control while she is out with friends at the mall, then blames and punishes the victim and makes her think it is her fault). If things proceed quickly, the victim would probably need to be bound, drugged, or otherwise controlled at all times once she realized what was happening. This is absolutely non-consensual torture and destruction of an innocent and unless she becomes completely psychologically broken she will never like it. I am not at all adverse to this going as dark as any two twisted minds can make it.
The drawing that kind of kicked off this idea is behind the spoiler tag. While there is nothing explicit about it, it is probably a little NSFW and if the above plot doesn't appeal to you, you probably don't want to see it.
As far as sex goes, I am really ambivalent as to its involvement. If it seems to fit in organically, or if it plays an integral role in breaking the victim, then I am all for it; however, it's not really my focus. I would prefer that the parent not be in this primarily for sexual pleasure but rather out of the twisted conviction that this is the right thing to do.
I am open to playing either role and would probably ultimately like to have one game where I play the victim and one where I play the parent.