Any suggestions on a book with great works building that also tackles darker aspects of humanity

I’ve only recently started reading, but the shows I gravitate to, are usually shows with very complex usually morally grey or even dark characters, I tend to enjoy when a book explores human behavior in a realistic sense in which you see how abuse/trauma affects them in a realistic way, where they themselves come out with warped morals(not exaggerated for shock value, and realistic in nature), The character doesn't have to be likeable, just interesting and we understand their thought process. I also like shows that can captivate me with their world, worlds that draw from reflected reality and is realistic, but unique and complex. I love to see parrelels to the world and how humans behave, systemically, maybe even addressing oppressive systems that mirror our own but more unique. It doesn't have to be fantasy or sci-fi, but I like those, could also be historical fiction ect. For instance, One of my favourite shows is Legend of The galactic Heros.