Screenwriter Alex Epstein explains "The Rule of Joss Whedon"

I’m working on my metaphysical pay cable series, and as a massive sf&f geek, I find myself tending to look at episodes from a point of view of "what is the cool sf&f antagonist in this ep ? And I have to remind myself of (what I’ll call) the Rule of Joss : don’t start with the sf&f antagonist. Start with where is the hero emotionally ? What is Buffy’s real-world emotional problem this week ? Now, what is the sf&f antagonist that best catalyzes that emotion or problem ?

In other words, if you have a ghost story, your story shouldn’t be about the ghost. It should be about the protagonist, and why she’s seeing a ghost. What is her problem that confronting a ghost will help her resolve ? It could be a fear she has to confront, or a bad decision, or a moral qualm, or likely a combination of all of those. But the ghost is only there, narratively speaking, to take your hero through her story.

It’s not the only way to write a ghost story. Many commercially successful ghost stories have nothing to do with where the hero is emotionally. The NIGHTMARE ON ELM STREET series, for example, are all about the villain. And even a nifty horror movie like DESCENT, which starts the heroine in a truly horrific place emotionally before she even goes spelunking, is really about the cave and what’s in it. But the SF&F movies I find stick with me the most are movies, first of all, about what it’s like to be the hero. BLADE RUNNER, even the much maligned theatrical version, is not primarily about the replicants and their desire to live ; it’s about Deckard and his humanity. (Which is why I find the director’s cut unnecessarily on-the-nose and self-indulgent.)

Start with your hero. What’s the emotional process you want her to go through ? Now, how can your supernatural antagonist (or science-fictional situation) put her through that process ?