My BF is a sadist. He felt a bit nervous about it...not ashamed or embarassed...but nervous of how I would view him when I found out (ie: think he was some sort of abusive asshole and leave him). So when he realized that I understood that was just how he was and he wasn't doing it maliciously, it led to a lot of great times in bed
It also helped that I enjoy being a victim, I've always felt more submissive than anything. I remember as a kid hearing stories about girls who were kidnapped etc., and they didn't really turn me on, but there was a part of me that got a bit...excited I guess.