I recently read a book about two brothers. One was a kind scientists, and the other quickly became a deranged religious nutjob. The two started on the same side, but then they came into conflict and stuff happened.
I bring this topic up because you could tell which brother was bad pretty much from the start because he was a dick. He was a military commander, but in the first chapter he sends one of his men to the brig because the man dared to point out that the commander was doing something dangerous. And then, I think in the third chapter, he almost rapes a woman.
I had a lot of issues with the book, but the one that works best for a Random Writing Tip is that you could either start with a character and follow them as they descend into darkness by making bad choices or whatever, or you can start with them as a rapist so the reader knows that they’re the villain. I can understand how with TV or movies you have limited time to show the villain becoming villainous, but by overplaying how dickish the villain is, you’re basically just having the character walk on screen with a sign reading “I’m the villain, hate me.”
I was trying to think of some good examples when I thought of Darth Vader. In his second scene he just murders a guy for not giving him the “right” answer. Is that dickish, or being a badass? By the end of the movie you know he’s a badass, but that scene is Vader basically wearing a sign reading, “I’m the villain, hate me.” So you can have your villain do something dickish, just make sure to establish them as a badass, and not just a deranged religious lunatic.