The protagonist of any story doesn’t matter very much unless you have a stunning rival for them to go up against.
Its arguable that everyone loves the villain just as much as they love the MC. But they want a realistic villain, which means as the author there are several things you need to figure out.
There’s some clamor for the evil, cackling villain who will kill anyone to get what s/he wants. I’ve certainly come across some creepy villains in the books I’ve read, but in my opinion, the best villains are the ones you can almost relate to. They’re the ones who have a logic behind their madness – a very twisted, maniacal logic, but a reason that makes some degree of sense nonetheless.
This is why it’s so important to know the villain’s back story. Understand what went wrong in their life to make them the villain. I really love the saying that everyone villain is just the victim whose story hasn’t been told because I think its very true. So give your villain something the readers can sympathize with. Understanding your villain’s back story also helps you to understand his goal. It’s the reason behind why s/he’s so awful.
Even the villain needs a weakness. Often the hero/ine discovers the villains flaw in the last, crucial moments of the book. If your villain has a weakness, it means they have some degree of morality. Is there someone they care about? Is there something they wont do no matter what? Give your readers something to relate with. Give your villain both good and bad qualities.
After all of this, after building up sympathy, this is where you still need to have your villain do something despicable. Something I really love is when the author manages to get the reader to believe the villain might make the right decision, and then turn back on that and remind you that this is the villain. Make the readers themselves question how they ever managed to fall in love with the villain. It’s much easier said than done.
Think about some villains in literature/films. What are the qualities that simultaneously made you love/hate them?
I have to bring up what is possibly my favourite villain. Loki, in any of the Marvel movies. It’s a largely known fact that there are a lot of people that actually watch the movie for Loki, not Thor. We’ve fallen in love with his back story, and he still manages to remind us time and time again that he isn’t a good person. So why do we still want to believe he is? I absolutely love Loki’s character. It has the continuous struggle between good and bad in one person.