The action world is full of memorable one-liners. Gangster films have sinister mobsters and ruthless hoodlums. Dramas are all about serious realism while screwball comedies can get away with fart jokes. Adventure films have exotic locales, but if you’re writing a western, you better have dusty towns and six-shooters. Science fiction scores with aliens and futuristic technology. And when it comes to slasher films, don’t hold back – the audience is actually rooting for the killer.
Understanding film genres (and sub-genres) is important, because let’s be honest: people rarely go to the movies to be surprised. They know the action hero will survive, that the girl will get the guy, and the villains will get their just deserts. Nobody goes to a rom-com to face reality.
The truth is that love is hell and sometimes the bad guys win, but in the movies, love is a holy elixir and the hero always saves the day. Screenwriting is not about reinventing the wheel. The key to writing a sellable script is to understand the genre and meet the expectations of its audience.