There’s a popular screenwriting book called “Save the Cat!” The book gets its title from the basic idea that every movie needs to make the hero likable and one way to do that is through a technique called “Save the Cat,” which is where the hero risks helping someone less fortunate than him or herself. This not only makes the hero likable, but also demonstrates the hero’s good nature.
In “Alien” you can see that the hero survives the alien because she tries to save the cat. While everyone else gets slaughtered, the hero survives with the cat. That just goes to show you that saving a cat can not only make you more likable but it can often spell the difference between life and death.
If you’re interested in screenwriting, don’t ignore the “Save the Cat!” books, software, and website. You can learn much about screenwriting just by keeping in mind that your hero needs to save a cat early in the story.