I think it's different for everyone, but try to figure what you like. I had a biting fetish when I was a child so it naturally progressed into rougher role play when I was a preadolescent. I believe it is important to determine what you and your partner are comfortable with performing so you should definitely discuss this with him. :] My ex-boyfriends were apprehensive when I first told them about my fetishes, but I think it excited them to see the extent at which I became aroused so they eventually became engrossed in it as well.
Haha, I used to do this with my ex-boyfriends. It's not the element of rape that's exciting, it's allowing your partner to do whatever he wants with you. It helps to know that it is your partner who is performing the act, not a stranger, so you can trust him to completely dominate you without harming you. It's just another form of S&M.