And because it's a 4-letter word
And because love, in one or another of its guises (romantic, gustatory, etc.) is a primary character motivator. This works for villains too--love of power, love of revenge, love of money, there's plenty of examples.
Ask: what do they love
And do they love it wisely?
That's a certain way
To recognize a villain
Or a doomed, tragic hero
Love this cheese , especially with grapes!