I read somewhere that today you give all the good lines to the stars, but that was not how it was in the time of e g Bogart. Then the good lines came from the character most suitable to fit the story. Could this be a theme? The good lines from an unexpected character? (When there are more than two possible talkers, of course) I'm afraid I haven't much of an example to share at this time. It is more of a thought if this is really true, and if it is working. I mean, the films of today are what they are for a reason. It may be good storytelling, or it may be vain actors, or something else. Just a thought.