I really enjoy playing either side of the Hero/Villain dynamic.
My enjoyment of these games is more from the mentality of a writer and/or an actor, so I love exploring the psychology of the character and examine what that might teach me or, just simply, what fun it might bring.
As with acting (and writing too), sometimes the most fun comes from being the villain.
Both in a fun and/or grand sense, but also in a very serious, psychological exploration.
When you can create a fictional being that is twisted and terrible... but you understand
how that (once pure) being became that way and/or why and how they do what they do... and what they think and feel about it and/or how they avoid facing the reality of what they do...
It is actually a powerful experience that can help you in dealing with people and problems of the real world.
Don't get me wrong. I can find just as much depth in a hero character as well.
However, I've never had any qualm with exploring the darker side.
I want to say, "within my fiction" at the end of that sentence, but it's more fun to just leave it like that, hahaha.
While I have a few seemingly shallow thugs, brutes and killers in my roster, really, they all have a layer of depth which created those aspects within those people.
My main villain, Malfaz, however, is an example of a very deep and tragic persona, tortured by physical and psychological ailments, that is both psychotic killer and a delusional, misguided vigilante, in a sense.
Then I have Zox'Oculox, who is an alien who is mostly a product of his evil, barbaric and disgusting culture. Zox is likely my most simplistic of villains.
I have many others that fall in-between he and Malzaf, but every single one of them is just a person/being whose experiences, personality, faults, quirks, weaknesses and strengths (plus consequences, circumstances and all) led them into being who they are.
Regardless... in terms of personal/player morality... it's all just pushing keys and buttons and making enemies' numbers go down while keeping your numbers up.
The rest is poetry, whether dark or light.