Checkmate, moral compass

That would actually be a pretty cool premise. A hero who promises he will kill himself once all evil is defeated, as what he does although for good is evil itself. But people love him too much so they themselves become evil to keep him around.

I guess kinda like a incredible situation, but more dark because the protagonist just wants to die instead of raise a family.

He could always, you know, just break their spine

So would the number of citizens in gotham. Apparently everyone is a killer in that city.