http://www.rawbw.com/~svw/superman.html

I used to have a cool superhero anthology that had a story called, I think, One of the Guys where a superhero with the origins of Superman goes into how alien he really is despite the outward human appearance. He has a strange diet, his apartment is spartan and the temperature and humidity are always really high and his choice of being a good guy comes from wanting to be social rather than a moral choice.