A complex, layered story driven by detailed, layered and complex characters

I've been searching for a book or series to scratch the itch left by ASOIAF: It's a series and world full of interesting, complex and layered characters coming into conflict with one another, all with their own motivations, histories, complexities and detailed characterisations driving an incredibly meticulous and interesting plot touchung on an exploring a multitude of complex themes. I'm looking for a book or book series, that can come close to what ASOIAF offers in this regard.

Just to be clear, it doesn't need to Fantasy or genre fiction at all. I'm open to any genre, even classic literature or non-fiction. So long as it's a story full of incredibly well-realised, interesting and layered characters navigating an equally interesting and complex story.