In superhero fan fiction, the 'violence inherent in the system' could be the way the authorities try to control superheroes. For example, they might impose strict laws that limit the heroes' actions, which is a form of institutional violence. The heroes then have to either abide by these rules or rebel against them.
In historical fan fiction, the system could be the monarchy or the feudal system. The violence here might be in the form of forced labor, unjust taxation, or the use of military force to suppress uprisings. Writers show how characters are affected by this systemic violence and how they might try to change or escape it.
In horror - themed fan fiction, the system could be a cult or an otherworldly power structure. The violence is often more extreme, like human sacrifices or mind control. Characters are usually in a fight - or - flight situation against this system - based violence, and the story revolves around their attempts to survive or destroy the system causing the violence.