Alright, how is this for a rough sketch of the setting:
A huge metropolis called Metro City, with shining towers that represent America's unparalleled wealth and status in the world. The world is much like the one we know today, with slightly higher technology and slightly worse separation between the haves and have nots. So down on the street levels of Metro City crime is rampant and the police can barely deal with it. There are rumors of some sort of shadows criminal cabal, maybe one with occult tendencies, trying to unite all the gangs. But the towers and green parks of Metro City are protected by Captain Victory and Lady Liberty, two mysterious heroes who appeared a few years ago and demonstrated incredible powers. (Both like Super Man level heroes) There are rumors of other heroes and so-called "mutants" in the city, along with vigilantes using technology, but surely those are just rumors.
So your characters would be heroes or at least anti-heroes just starting down the paths of becoming a superhero. If you create a character, a description of what you want your powers to be and describe what you would like your origin story to be, I can PM you and we can play that part out privately now before the main game starts.
edit: one of you playing a villain would be fine too, but require a little more behind the scenes work.