The character bio of the antagonist in your story is as important as the protagonist. Sometimes it’s difficult to remember that the bad guy has to be as completely fleshed out as the good guy. He needs personality traits, he needs general repetitive sayings, and he needs motivations. A truly believable monster will have a definite reason for what he’s doing.
I try to think of it as an experiment in profiling. Whether you are using a supernatural creature or a human being, you need to know how your monster came to be who he is today. Fully knowing his back story will help you write him better. You don’t have to give your readers his entire life’s story, but knowing it will help make him more believable.
Let’s take a look at some popular monsters and see how they add up in the believability category.
Made of many different men. Amazing strength. Lacking intelligence. Capable of strong emotion. (Uh oh....there’s the culprit right there. Strong emotion is what drives poor Frankenstein. Most of us can identify with him because we are also capable of the same thing. His emotion controls his motivations, so we understand why he’s doing what he does.)
Locked in spirit realm, can only interact when the victim is in a dream state. Omnipotent in dream state. Can control every aspect of victim’s dream. Deadly. Warped sense of humor. Filled with rage. Seeks vengeance on everyone he can find. (Uh oh.....again strong emotion. Freddy was burned alive by the parents of the children he allegedly hurt in real life. He genuinely feels the need for retribution.)
Seemingly unemotional. Serial Killer. Highly intelligent. Vicious, brutal, sadistic, narcissistic, psychopath. Now Hannibal is much more complex than the previous two characters. Throughout the books we see traces of humanity. We do see some emotionally motivated actions, but for the most part he seems incapable of any real emotion other than anger. Until you get to Hannibal Rising. When you go back to the beginning and see all the traumatic events he endured, your initial hatred and disgust for the monster transforms. By then we can clearly see how he ended up being who he is and why he kills.
These are the things that make a monster unforgettable. And that’s exactly the type of antagonist you want to have in your story. So when you are writing, don’t skimp on the bad guy. Be sure he has grounded motivations for what he’s doing.