I have a problem with writing villains: I always sort of fall in love with them and then want to redeem them, even if they've done really bad stuff. Darth Vader coming back to the light after destroying at least one planet and every innocent soul on it? Yes. Thanos getting his sought-after retirement in a golden field after dusting half of life in the universe? Okay, I can see it. I confess to a similar soft spot for Dracula, the creature in Frankenstein, Annatar in The Silmarillion (he just wanted to be pals with pretty elves and make jewelry, what?!).
Personally, I spent the entirety of a book creating a dude so bad he tried to kill his own child... and then two more books explaining why he really thought he needed to and felt terribly bad about it after, and also he had great hair.
See? It's a problem with me.
I think my favorite villain, though, is Prince Nuada in Hellboy 2. If you haven't seen the movie or read the novelization, I'll just rec those right now. He's not only immortal, a warrior, an elf, and a prince, he's also such a badass and really does care about his people and his planet. Like, maybe too much?
And that might be the trick, for me, to making villains angstily relatable: they love hard. Too hard. Sometimes it corrupts them or leaves them vulnerable to temptation. But if it all starts with love, they can't be completely lost, right? I mean, that's what I learned from Luke Skywalker.
Of course, now I'm a grown-up human and absolutely believe there's no such thing as an unredeemable villain, and the best stories are the ones that prove me right.
(Spoiler: Not all the villains mentioned in this post were, in fact, redeemed. In fact, most were defeated, ultimately. Still.)