It Follows- Questionable Characters

From https://www.slantmagazine.com/film/interview-david-robert-mitchell/

With the way that the film is structured, there are rules, but they aren’t so certain.

MITCHELL: The rules exist within the film, but based on what the characters have figured out. So you can only trust them as much as you trust the characters. I myself, as a filmmaker, don’t say these are the rules, but I say that these are what the characters in a difficult situation have figured out. As opposed to saying that the film is saying that, I’m saying that the characters are saying these sets of rules. They seem mostly right, but they’re questionable.