Such as the victim being too young or related to you?
Being honest here...
Actualy I fairly often have fantasys like that; about twice a week (less often then before, but I stil get them). I got myself out from a "forbiden area" like that, vhen I vas a teen, family abuse/rape, and I vas the victim. Vent on for almost 5 years (vhen I was 15-19), not all the time, sometimes almost a month passing in-betwen it, but generaly conzistently, before I got strong enogh to break with it by killing my father, vhen he tryed it one last time.
So yes, I do have fantasys like that, but (this ones for Trill and all the other mods, so you dont freak out) I dont take them to this site, they stay in my head; if they didnt, I'd probably fill the Taboo board vith storys. I read the rules tho, and I wont post shit like that here. But I'd be lying if I claimed I dont have them. They are from both perspectives, both roles, rapist and victim, they contain moderate-to-heavy amounts of verbal and phyzical abuse, and they all end up the same way, rapist geting brutaly tortured and killed by the victim (probably because I didnt actualy torture him irl, I just killed him, and I often vish I culd have punished him harder then just death).