A character with this goal is motivated by a twisted desire to break the will of others. Oftentimes, the most effective way to accomplish this is to divest the victim of what they hold most dear: the morals and deep-seated beliefs that define them. For a character who is more concerned with the beliefs themselves and bringing other people to their way of thinking, see FORCING A CONVERSION.

Torturing the victim
Brainwashing them
"Mentoring" someone with the goal of breaking them and rebuilding them in the character's own image
Putting the victim into no-win situations where an impossible choice must be made

There are five basic human needs that, when missing from a character's life, could motivate them to pursue this goal. The following needs are all possibilities, but only one of them should be the primary driver for any given character. For more information on the relationship between human needs and outer motivations, please see this Character Motivation tutorial.

Esteem and Recognition: People with this motivation are often power-hungry, believing that gaining this level of authority over others magnifies their own superiority and esteem.
Love and Belonging: A character who has never known love (or has only known a twisted version of it) may lash out against the real thing by trying to purge it from society. Because love is at the core of many people's moral codes, altering those morals could be a good way to accomplish that purpose.