The term 'Payback Seeker' can be summarized as an AVENGER. This term is often used to describe someone who seeks revenge or retribution for a wrong that has been done to them. It is usually used in a negative context, as it implies a desire to harm another person in order to get justice. The term is often associated with vigilantism, as the person seeking payback may take matters into their own hands rather than relying on the justice system.