Genres are sacred. Well, sort of.

If you’ve followed entertainment trends over the last thirty years or so, you’ve probably noticed stories which fit in a single genre -- “it’s a science fiction novel,” “it’s a children’s book,” etc. -- are being overtaken by a new approach: mix and mesh and mock. We can enjoy children’s books or children’s horror novels ("Coraline"). We can enjoy crime films or parody/pastiches of crime films ("Pulp Fiction") We can enjoy period-piece musicals about historical figures or hip-hop/rap musicals about historical figures ("Hamilton").

None of this is strictly bad, of course. One of the big secrets about genres is that they’re much looser than people realize and, as authors Kazuo Ishiguro and Neil Gaiman commented in a New Statesman article, genres often exist simply because they help bookstores organize shelves. Gaiman argued in another interview that really the wave of genre-mashups and parodies is like fusion cuisine. “It’s that point where you go, ‘OK, there is actually no reason why I can’t combine this food and this food to create a taste that nobody’s actually ever had before but once you’ve had it you’re going, “Well of course! This makes complete sense!”’”

I think fusion cuisine is a great way of looking this trend, because the thing about cooking is you can try new things but you must respect each food. You have to understand what kind of texture and taste a particular food has, and a good cook knows that some things absolutely won’t mix with that taste and texture. You have the freedom to try anything, but you must respect each food’s uniqueness. When you don’t, you get unfortunate things like ketchup mixed with vanilla ice cream.

Similarly, in storytelling you can try anything, but if you disrespect what makes each genre special, you get a second-rate story. One of the best examples I’ve seen of this was the movie "Batman Vs. Superman." The film opens where its predecessor left off -- with Superman fighting an evil alien and destroying Metropolis in the process -- and we discover Bruce Wayne was in the city at the time. Wayne appears shocked, like he’s never seen this kind of destruction or power before, and it starts the chain of events which makes him decide Superman must be eliminated.

This would work fine -- if the movie was mainstream science fiction like "Independence Day" or "Close Encounters of the Third Kind" where the audience can assume aliens have never shown up before. It might have even worked in the "Dark Knight" trilogy, which assumed there were no paranormal foes to deal with.

But "Batman Vs. Superman" was a superhero movie with all the usual props and gadgets. It gave us every reason to assume it was a typical superhero story -- and in those stories, a superhero can face anything up to and including the devil himself in a typical workweek. A new villain may bulldoze Manhattan, paranormal monsters may appear from a rolling cloud of ashes, and a time traveler may twist reality like aluminum foil. On a really bad day, the hero may go through all that and then his girlfriend dies, and he has to recruit a demon to get her back.

In that context, aliens attacking Metropolis is almost predictable. In a typical superhero story, Bruce Wayne should have seen Superman and thought, “Oh, aliens. Figured this would happen sooner or later." But one of the screenwriters either didn’t understand or didn’t respect the genre he was working in, and audiences got a mediocre movie.

Writers have more freedom than ever to innovate and try new angles in storytelling. But if they don’t respect the things which makes different stories unique, they risk creating poor stories.