Submissive - describe a person who is obedient to others that are dominant.
A submissive person can be a slave, or an individual who is at the bottom like being whipped, tied up, humiliated etc.
There are many people who fantasize being submissive especially in the live video chat world. On Xlovecam is rather easy to find a dominant performer with who a submissive person can spend unforgettable moments.