Of course, you’ve heard it before. Antagonists work better when they themselves are whole, well rounded people, not just bogyman punching bags for the protagonist. And as they say, even Hitler had a mother.
So, who loves your antagonist? Who looks up to him or her, or smiles when they walk into a room? When you’ve got who, why? What is it about your antagonist that makes them lovable?
Think about great bad guys like The Joker, or President Snow from Hunger Games. Harley Quinn adds so much to The Joker’s personality. And the fact that Snow’s got a granddaughter that loves him gives him a whole new dimension. I mean, he’s sending kids this little girl’s age to die.
Write about who loves your antagonist for ten minutes. See if you can’t gain some new perspective on your story because of it.