Audiences are bound to focus on the events that happen when the unstable Julie, doing some snooping of her own, discovers that Sarah has incorporated her into her new book. What we see is a clever tease and Sagnier is absorbing to watch. She plays Julie as almost too childish to be truly slutty (i.e., unaware of what a reputation might be worth) or malevolent (as opposed to merely destructive). She gives her a spoiled-brat premorality and a superficial precocious toughness that gives way under pressure. It's touching-spooky when her identity smears; Sagnier as Julie is a hardboiled white with a raw yolk inside.

But the movie is out of the ordinary only as an externalization of Sarah's working process. It doesn't matter whether the plot is "real" or not (implicitly it's a series of what-ifs strung together by Sarah); the structure of what we see is allegorical in that Julie represents the disturbed, sociopathic parts of Sarah that she contains but that lead her to write lurid crime fiction. It's all a welling-up of the turbulent, sordid imagination that enables a woman you can't imagine being very popular to touch a popular vein as a writer.

As Ozon explains in this interview with IndieWire:

iW: Your cinematic self-portraits are filled with mayhem. Where do the perverse, homicidal impulses come from?

Ozon: My parents taught me something when I was young: when you create something artistic, you can throw in all the horrors of life, everything you would never actually do, all sorts of violence--it's an art work, so it's okay. As a child I was allowed to read Sade because it was imaginary. Fritz Lang once said, "If I hadn't become a director, I'd be a murderer. Better to have murders in movies than life."

iW: So these violent impulses are a part of you?

Ozon: Just like everyone else. We're all potentially murderers. You have murderous impulses too.

iW: I'm not particularly in touch with them.

Ozon: Whoa, that's dangerous! [We laugh]. The role of the artist is to be close to those impulses and express them for everyone else. Why do you think there's so much violence in movies? And why are all those violent American movies so successful? Because everyone has those tendencies. And seeing them on screen is cathartic.

Movies that satisfy our taste for violence are a hell of a lot more common than ones that feature a protagonist who's a hypocritical killjoy. Like Malvolio and Tartuffe, and their descendants Frank Burns and Hot Lips Houlihan in Robert Altman's M*A*S*H (1970), they're always off to the side. (Tartuffe is more central but he's emotionally marginal--it's assumed we won't identify with him.) This makes sense since these are characters who put a chill on group experience, on the open indulgence in pleasure. They either have to be ritually expelled from the group like Malvolio, Tartuffe, and Frank Burns, or converted like Hot Lips (and Hermocrate and Leontine in Marivaux's Triumph of Love).