What is the purpose/story of david bowins song ''heroes"?

David Bowie wrote that song (and performed it) for a movie called Christiane F. I think it was back in 1981. The movie's main focus was on heroin addiction, and life on the streets of Berlin for a child prostitute. Probably one of the most depressing movies I have ever seen. The song goes perfectly with the movie.

I don't know exactly, but he and Iggy Pop were living in Berlin at that time, behind the iron curtain, and I think he was thinking of the world's big picture. Check out Iggy's Lust for Live to hear the other bookend to what was going on there. Makes me think he was singing about the two of them sometimes.