Villains, yes, the evil doers in our stories who piss off the main characters and make their lives a living hell. Well all love to hate them and, really, what would our stories be without villains? Nice, sweet tales that are boring as hell.
But let's remember, villains are people too. They're not warm-fuzzy types everyone wants at their party, but they did have hopes and unrealized dreams, just like us. The difference is, while we got over it, villains stomped their feet and became psychotic.
I love a good villain, but to have a truly good bad guy or gal, it's not enough to just accept that they're evil. I need to know why.
In my paranormal romance, the villain is a nineteenth century ghost, hellbent on killing my heroine. Why? Why try to murder a perfectly lovely woman? I needed to explain her descent into darkness.
She had been in a loveless marriage and the only joy in her life, her daughters, she had to disown. The villain turned bitter and eventually murdered an innocent woman.
What does this accomplish? Well, for one thing, it offers a reason for her actions. But it also allows the reader to have just a teeny bit of sympathy for the villain, someone who wanted to love and be loved, but had all the joy sucked out of her life. It shows she was once human which, I think, makes the impact of her evilness that much stronger.
Layering your villains is just as important as layering your protagonists. And if you do it right, who knows? Maybe you'll be lucky enough to have Alan Rickman play him in the movie :)