If we prefer the devil we know, do we prefer a villain with depth?

I’m about to add scenes that develop the villain; I’ll alternate the new scenes with the current, hero’s plot. But does it make sense to break up the story? Why add ambiguity and irritation by interrupting the main storyline? Will the new scenes be extraneous; will I write them only to rip them out?

The decision to circle back to create new scenes was not easy; I hope they’ll lend authenticity and conviction to the villain, bringing dimension to the hero’s challenge and underscoring the impossibility of stopping this runaway train.

It’s not like the idea is new; there’s ample precedence for alternating theme a with theme b. Hero movies such as Robin Hood, Superman, Batman, X-men, and Iron Man flip back and forth between hero and villain until anticipating the clash is nearly as thrilling as the conflagration itself.

But many stories don’t weave between hero and villain. To mention a couple of recent favorites, Philippa Gregory doesn’t; in The Other Boleyn Girl, Henry VIII is far more myth than man. The same could be said of Lauren Weisberger’s villain in The Devil Wears Prada. Examining old favorites, in the Belgariad saga David Eddings never introduces an enemy until 5 minutes before he’s obliterated. The same is true of Piers Anthony’s quests – the story unfolds building a team and discovering their strengths and weaknesses. The villain is little more than a shadow.

How does revealing the villain affect the coherence and impact of the story?