Okay consider a world where superheroes are beloved like all comic books correct? They save the day and have to deal with no collateral damage. Well in this one the superheroes are f***ed up. Think of it as the justice league rated X.
The CIA has a certain group lead by a Michael Caine sounding man who "takes care" of the super heroes. Literally the first chapter is the main character with his girlfriend and the superhero is fighting a villain and he throws the villain accidentally in her direction crushing her against the wall and killing her. Your captain America/Superman character is a sociopath maniac.
Obviously all of this gets swept under the rug because the super heroes work for the government and they don't let their dark personas out in the public. It's a good read tho a lot of twist and turns and some crazy shit you don't expect.