These Shoes are Just Creepy!

Seriously, who would wear them? If the point is to scare, they don't accomplish it. They do nothing for me. Well, they do kind of gross me out. But other than that, nothing. In The Fire in Fiction, Donald Maass discusses the antagonist, the villain, the doer of all evil. He says that in the work submitted to him, most of these mean-spirited characters fall flat. Why is that? Well, because they have no depth. He or she is just bad by default without explanation, and just really aren't that scary. Mr. Maass suggests that one way to fuel fire into our writing is by giving the villain some human characteristics and a reason for acting the way he does. He can't just be bad for the sake of being bad. The reader won't buy into it. Maass even goes so far as to suggest that we make him somewhat endearing to the reader. This adds great depth to a story. My primary antagonist is somewhat ambiguous and needs to stay that way, so this is difficult for me. I'll be thinking about it during my rewrites, though. In the mean time, I'll be applying it to my secondary antagonists. Is your antagonist just bad for the sake of being bad? Or have you given him some motivation for his behavior? Please share.