Villain Rewrite: More Daunting Than the Villain Himself

I'm undergoing a major rewrite of my main villain's character, and it's really whupping me.

At first he was the intelligent, insane, aggressive, sarcastic monster that people really enjoyed when they read him. But eventually I realized just how stereotypical and static he was, and decided to rewrite him. Now I'm making him just as intelligent and sarcastic, but now his insanity manifests itself as a 'coldness' in his brain that takes control of him in combat or when he is enraged, deadening emotion and moral consideration. Any tips on writing this? Should I include a snippet to demonstrate what I'm talking about? It's a bit confusing, I know.

Make him love something.

Like...cake?

xD Cake works, I guess. But I think Snoink was referring more to making him vulnerable by being attatched to something-- whether it be a person, and animal, or an object. If there's something out there that this villian truly loves and cares about, then that gives him a softer side *and* a weakness. Because then that person, animal, or object --maybe even a place-- can be taken away from him.

Love, also, makes a person human. If you have this constantly evil and sarcastic monster, but he doesn't seem to feel any of the more tender human emotions, readers won't be able to relate to him as well.

To expand on that even more, since love tends to be the main weakness of people.

In my novel, my villain has a great love for his son. Even though the way the plot goes they are on opposite sides, the villain wouldn't harm his son/ We later learn he wouldn't harm anything or anyone his son loves, for reasons readers find out later. (He's harmed someone his son loves before and can't stand to see the pain it causes him). It also allows the MC to walk away with her life. Deux ex machina is may be, but it fits because of proper foreshadowing.

Hmm, well part of the reason he's bitter, sarcastic and unbalanced is because he loved and lost. The setting is also somewhat...limiting. He's with only six other characters, a situation that does not and cannot change. I'm trying to mix up his interaction with other characters, where occasionally he breaks his more antagonistic side and admits that he is afraid of his darker nature.

I believe strongly in Tabla Rasa the theory that everyone is born completely neutral and events in their life lead to their future actions. You know your characters history translate that to his now evilness.

I'm just spit balling here because I know nothing about you're story but lets say a friend of his was being mugged so he goes over and tries stop it. He becomes almost detached from his body and all he can think is I have to protect him. So he kills the person without realizing it.

My suggestion have him thinking about whatever it is that drives him when he's doing his horrible acts of evil have these be his justification.

pm me if this doesn't make sense

I agree with Amon. Look at the moments in his life which have brought him to where he is. That will make him a character rather than a concept. Remember two things, which may seem contradictory;
1. You're the author
2. If your characters are developed, they should be leading you, rather than you leading them.