1.

They’ve got attitude. They’ve got spunk. They’ve got a will to live-and a will  to kill. Perhaps it’s the third-person-point of view that does it-experiencing the antagonist’s insanity through their eyes. Perhaps it’s a famous catchphrase, or simply a name (“My name is Pennywise, the dancing clown!”), that anybody loves. In writing Little Threats, The Voice has a cold menace-type attitude to it. In Star Wars (yes, I went there), the Emperor has a “suave”, and a smooth killing attitude about him. These things make an antagonist loveable.

2.

It’s got hatred. It’s got a killing pattern that you just don’t want to stop. Room 1408-a Stephen King short story’s antagonist-killed every person who ever slept in the room (seemingly by natural cause, or suicide). While the natural deaths seem legitimate, the main character in the short story, Mike Enslin, see’s the real side of the room-which transforms hideously into what can only be described as a giant stomach. In Carrie, her killing seems justifiable, which makes her killing all the more interesting. PennyWise the clown had a eating cycle every couple of years, which ends abruptly enough to keep cops from discovering (though even if they did, It owned Derry).

If you want to make your novel a million (times ten to the thirty-eth power) times better, make a loveable antagonist. Gruesome, psychotic, preferrably with animal-like characteristics.