So, I want to write villains and want them to really play the part. But I read on this site that villains can still send harmful messages or be hurtful to the audience if you’re not careful. How can I make my villains really evil while avoiding such pitfalls?
It sounds like you’re concerned about exploitation, which means using the pain of marginalized people for the benefit of privileged people.
Most types of sensitive things a villain could do in this category aren’t actually logical things for villains to do. A villain threatening to kill someone’s family is just fine and often a logical move for them, whereas the villain committing rape or threatening rape is insensitive, but rape also has very little tactical use. You don’t need rape to make your villain super evil, and your villain won’t have any reason to rape someone unless you specifically set out as the storyteller to give them a reason.
The same goes for most other kinds of hate crimes, bigotry, or other things that are particularly sensitive. Storytellers reach for those things because they’re shocking, not because it’s the only reasonable thing for their villains to do.
If you want to put in something that isn’t strictly exploitative but could be unpleasant for readers – for instance, your villain is going to torture a fake confession out of someone (not torture to get information, that doesn’t work and spreading the idea that is does is harmful) – you can just do that offscreen. Say it happened, but don’t show it. If readers don’t have to read about it in graphic detail, that makes it a lot less unpleasant for them.
If you do decide to have anything unpleasant depicted in detail, providing content notices will help readers who could be hurt avoid reading it. Just put them on a back page, and then provide the page number somewhere in the front pages where readers will see it.
That’s probably as much as I can say without knowing what you’re planning. The trick here is knowing what issues are sensitive for people. Once you know that, it’s unlikely you’ll have to choose between avoiding those and making your villain behave ruthlessly.