Answer:
Power, those that gain little power and are physically stronger in a relatiinship can easily get what they want. The abuser, in some sick way, finds joy in ones pain and feels pride that they have the power to control one by fear. This power to control the victim by fear causes the victim to feel trapped and obligated too keep feeding their abuser their power that they feel like they have. The abuser usually wants to be controlling of everything, once they get what the want their joy, pride, feeling of power keeps growing.
I hope this helps ^-^
