Switching
Some practitioners of BDSM enjoy switching—that is, playing both dominant and submissive roles, either during a single scene or taking on different roles at different occasions with different partners. A switch will be the top on some occasions and the bottom on other occasions. A switch may be in a relationship with someone of the same primary orientation (two dominants, say), so switching provides each partner with an opportunity to realize his or her unsatisfied BDSM needs with others. Some individuals may switch, but may not identify as a switch because they do so infrequently or only under certain circumstances. Sometimes individuals switch in just physical roles (top and bottom), and sometimes individuals may switch completely in emotional roles (dominant and submissive) as well.
People who top are called "tops," people who bottom are called "bottoms," and people who switch back and forth between topping and bottoming are called "switches." A switch can be a top in one scene and a bottom in another. Some people switch back and forth often; others switch only between scenes, but retain one role throughout any individual scene; others switch only very seldom with people that they trust very deeply; and still others never switch at all.
If you do switch, and you're not sure which role you want, you can play with that question in itself. Whole scenes can revolve around the "who's on top?" question. Maybe you can have a wrestling match, and the person who gets pinned first will wind up being tied up. Maybe you can set a timer, and when the timer dings, it's time to switch positions! There are as many possibilities as your imagination can dream of!
It is also the case that there is no necessary relation between whether someone is dominant or submissive in everyday life and whether they are a top or a bottom. Some of the most domineering executives secretly love being abased and abused; it's a chance for them to lose control, to give up responsibility. And some of the most quiet, meek, shy-looking people you've ever seen turn into demonic geniuses of pain and pleasure when given someone to play with.
See also Bondage:
