Pages and pages have been written on the topic of pantsers and planners. If you’ve been a writer for any amount of time, you’ve probably encountered the terms at some time, and chances are that you have strong feelings about which way is best, or at least which way is yours.
Me, I’m a planner. At first I thought it was a pantser, because I wrote my first novel without any kind of plan at all, and it turned out fine. (Relatively speaking.) But this turned out to be an anomaly: I was able to write my first book without any written plan because I had been planning it in my head for ten years. Once I moved on to fresh stories, I found that I needed a plan, or else I got lost and the story died.
However, nearly all discussions of pants vs. plan that I’ve read focus on plot and structure. Character, insofar as it’s mentioned at all, is either assumed to be part of the plan (by the planners) or to flow from that same wellspring of mystical inspiration that gives you the rest of the book (the pants). Here is where my technique is different from both the average pantser and the average planner: I plan my plots, but I let my characters take care of themselves. I know who the characters are, of course, but I don’t really know much about their personalities, histories, vices, or virtues before I write the story.
When I say this, a great many writers will recoil in horror. The problem, they say, is that then my characters will be lifeless, mindless plot-puppets going about and doing things because I, the author, have decreed it, and not because it flows naturally from the characters’ motivations. I had this fear myself when I first started this habit. But I discovered that my fears had no basis. The characters I created this way did not read like plot-puppets, but were as fully-fleshed as any other character I ever wrote.
The reason for this is simple: character is established by action. What this means is that it’s possible to learn about a character, even one that you’re writing, by observing what he does, in much the same way that you learn about the character of those around you by observing their actions. If your protagonist saves a kitten in chapter one, and punches his wife in chapter two, that tells you something about who he is. It isn’t actually necessary to have an elaborate understanding of his innermost thoughts in order to write his character; merely knowing what he does can be your starting place. In that way, your plot outline can suffice as a character outline. Your characters are the sort of people who will act in the way that your plot specifies.
If you do this badly, you can still wind up with bad characters. But generally these problems will already be visible in your plot outline. If the plot is implausible and unmotivated, then your characters will be implausible and unmotivated as well. But if your plot is taut and consistent, then in general the characters you discover while writing will hum.
The only downside to this is that I know my characters much better by the end of the story than the beginning, and I sometimes have to revamp the character’s thoughts and interior monologues from the first part of the story when I rewrite. But as writing problems go, this barely qualifies as a nuisance.