I: Kansas

(Three men watch as their house burns, huddling together on the hood of their car. The youngest is six months old.)

Every dramatic universe, just like ours, has its laws. They define the tone and intent of the story as much as they are affected by it, because they describe what is possible. The rules of a given show are its narrative physics; they also describe what it is that keeps viewers coming back. A show that falls off the beam, so to speak, has let its viewers down by not obeying its own rules. Either by making sense with the stuff that happened before, or by retroactively redefining the laws themselves, each new episode of a show has the duty of integrity. (The revelation, in the show’s final seasons, that the power of the Slayer comes from a not so-divine source, for example, puts Buffy the Vampire Slayer’s ethics on shout in a way that could hardly have been presumed from the start, but definitely fit with the show’s overall ethos.) Everything prior in the story must agree with new events, or else they must be explained in the stories to come. Otherwise, you’ll have your viewers jumping ship.

Coming-of-age dramas, like other basic forms of storytelling—fairy tales and classic mythologies, for example—bear a further responsibility to their own integrity. Every Young Adult novel or teen show is also a mystery story, because its entertainment derives from the fact that the characters are learning about the  …