Well, it's not some club you join, with by-laws and an initiation rite. The only thing to fear really is your own inner desires and inhibitions. No one is going to turn you into something you aren't.
D/s is what you make of it. It's most basic premise is a power exchange, one partner gives up control, the other one assumes the responsibility for being in control The one in control does get his/her way for the most part. But, it's a lot more complicated than that, because of course a submissive can always say "Hey screw this", and walk out the door.
There are those that play casually just as there are in RL vanilla relationships. There are those who are more serious about it, and there are those that live it 24/7. No one gets coerced into it, just as no one becomes gay by having a gay friend. It's a lifestyle and a sexual orientation. But, it all has degrees of Dominance and submission, just as anything in life.
Partners communicate and get to know one another just as they do in real life, and some don't take the time at all, just like in real life vanilla relationships. You'll see it all.
Mind you I am talking about D/s exclusively now, not B&D or S&M, which are different in scope and POV.
Just remember, not all submissives are masochists, some are, but not all. In fact, submissives and masochists are really different animals. Submissives have service at the core of their sexuality and masochists have pain/pleasure at the core. A masochist does not necessarily submit when s/he is receiving pain, especially since that's what they want in the first place. S&M can be devoid of power exchange, and only a mutual activity where one gets hot by giving pain, the other by receiving it.
Sometimes a submissive can be both, but even then it will be in varying degrees, and often the endurance of pain isn't about pain/pleasure [although again it Can be], but about pleasing the Dominant/Sadist.
Like I said it is complicated, as complicated as human sexual behavior. The community has been lumped together under the acronym BDSM, but even that is a misnomer. BDSM no longer resembles the leather S&M of the 50's and 60's, it's much more main stream now and has many, many different manifestations.
I'm curious, what about this is so fascinating to you? The sex? The dominance? The service? What?