Ok then how about this. It starts off as us being good but the city itself sees us more as a burden thanks to the destruction we cause when fighting baddies. So instead of us being heros, we're seen as villians and so someone or a group amongst the rest of the population step up to stop us. After a while we're just like "fuck it" you want to see us as baddies well then here ya go!" 

Later on something much bigger and more powerful than us comes along and we have to stop it despite the rep we have been given in order to bring about honor to our team.