Within human relationships there may be a submissive partner. This partner may be trying to appease the other(s) through agreeing to their command. If they are otherwise healthy this partner may be content. If one or both of the people are experiencing chronic, pervasive emotional distress then the relationship or individuals may require reevaluation.
People who are eager and willing to take on a recurring submissive role in a relationship or who fetishize the trait of submissiveness may seek out others that share their interest or form long term pairings based on consenting to heightened levels of submission in a relationship. This may be incidental in certain cultural or social groups, or may be explicitly expressed in others such as the BDSM subculture, or the Taken in hand subculture.
A complimentary trait to submissiveness is assertiveness.