Specifically, I’m thinking about antagonist motivation. We’ve all watched a movie or read a novel where the “bad guy” seemed to act simply because the plot needed him to act that way. I always try to make sure my characters—including the baddies—do what they do for good reason. But the question I ponder is if sometimes a bad guy can just be a bad guy. As a reader, do you need to know why a serial killer became a serial killer or can you just accept that he is? Do you need to know how the stalker knew where the girl would be, or can you just accept that he did? At the end of a story, do you sit there and contemplate all the loose ends? Do you need an explanation for every action taken by a bad guy?
Obviously, if we’re talking about Criminal Minds or a novel that profiles the antagonist, then you’re going to want more details. You’ll need to know the inner workings of the dark mind. Or if it’s a procedural and the good guys are hunting down the bad guys by examining their actions, then sure, you’ll want details. But what if neither is the case? How much do you want? How much is too much? How much is too little?
In my case, I generally want the details, just because I’m a bit obsessive about things making sense. I don’t necessarily need to know why your bad guy did what he did, but I need to know that you know. And maybe that is all part of how the story is conveyed. Or maybe it depends on the reader. Either way, what are your thoughts? You’re the target audience, so tell me—the author—what you need to know? Where is the line?