The day they met for the first time was spent in a San Francisco park. We talked the entire day. River felt the theme of the movie was the difference between love and sex. Noticing this, Van Sant allowed him to write some lines for the movie - the campfire scene. In society there's this confusion between love and sex.
People think they want love and that they'll get it through sex.
Mike is very clear on the difference between love and sex because he has sex for a living. I'm so glad I wrote that line. See Sounds of a Phoenix . River sunk himself so deeply into the role of Mike Waters it seems he was unable to find and return to his former self. I've never seen anybody so intent on living his role.