Those who are part of a relationship often exert a great deal of control over each other, but a controlling person will have more than their fair share. Their life is often dedicated to ensuring they keep the other person right where they want them, and keeping them ignorant of that control can be an important step. For those who have realized their partner is doing their best to control them, manipulating a controller might be their way to add balance to the relationship.
It takes a great deal of energy to control the life of another person, so it often means the controlling personality has a few blind spots. They might not see their partner is exerting their own brand of control when they play up to their ego, or they could be immune to recognizing that a goal can be used to put them into a frame of mind where they give their partner what they really want.
Keeping tabs on a partner is easy if there are good lines of communication, but those with control issues often try to limit the amount of information their partner receives from outside the relationship. Modern electronics make it easier to communicate with friends and loved ones, so a person who finds they are being controlled has that option to help them begin to push back on their partner. It might take them some time to perfect their approach, but it will be worth it if they succeed.
Partnerships are meant to be balanced, but some of them might simply appear that way. A person who has chosen to control their partner completely will do their best to make it look good, but their goal is to keep it balanced solely in their favor. Their concentration on this one facet of the relationship can make them vulnerable to being manipulated, and it can give their partner an opportunity to tilt the scales back in their favor.