I'm looking for a man who secure in himself and is content single or partnered. Someone who is equally happy debating whether Hawkeye or Black Widow should get their own movie as they are having a serious discussion of the latest exoplanet discoveries. Who isn't afraid to try new things. I'm not the traditional type, so while I'd like a committed relationship settling down into a conventional marriage just isn't what I want out of life. I find kids to be too overwhelming for me to be around and I never want to have any. If you're a parent I have loads of respect for taking on that huge responsibility but we're not going to be a match.
BDSM is a pretty important aspect of my life. I don't put this here to get anyone's hopes up that I'm just looking for kinky sex (BDSM isn't about sex for me), just as a warning to people who are squicked out by it. I play pretty hard and not everyone is up to it.
About the "mostly monogamous" thing. I'm open to dating someone polyamorous but it's not something I actively seek out or need. I'm also perfectly content being monogamous. However, I do expect to keep playing with other people in a BDSM context, especially if my partner is vanilla, but the extent is negotiable.