Hey, I remembered to post today! *gives self a cookie*
My current (and perpetual) WIP is a Ghost Book. Ooo, spooky. It'd be really easy (and fun) to make the "bad guy" ("bad guy" sounds like such a kiddish term. But antagonist sounds too uppity. Dilemma.) one of those evil and twisted bad guys who lurks in corners or murders people in their sleep or something equally delightful. Which is expected in a Ghost Book, and happens in mine. Fear not.
But I always like to make things a bit more -- interesting.
I've always been in love with the idea of a lovable bad guy. One of those bad guys you find yourself rooting for until, you know, they get everyone killed. Like Lord Marke in Tristan and Isolde (I can only think of movie references now. I blame my mono brain). Granted, he wasn't the "evil evil" bad guy, but he was the obstacle that kept Isolde from being with Tristan. He was just so gosh darn lovable, to the point where I almost wanted Isolde to realize the value of her marital vows and tell Tristan to get over himself.
What made Lord Marke so gosh darn lovable was how much we knew about him. We knew his background, saw his wife and unborn child get murdered, saw him sacrifice a limb (literally) to save Tristan. He was flawed and passionate and stood for something, and we knew exactly what he was fighting for the entire movie. And this thing that he was fighting for hit home even more by being something we ourselves could fight for.
The trick of making a bad guy a lovable bad guy is just that -- making his fight just as understandable and sympathetic as the MC's. Though whatever the bad guy is fighting for is ultimately something that will change the MC's world in a negative way, it should be understandable. The bad guy's motives and reasoning should be as clear as the MC's, even if whatever the bad guy wants isn't something we as readers would want.