The Cloven Viscount is the first book in a trilogy called Our Ancestors. I read the second book, The Baron in the Trees, already, but the sequence of books doesn't seem especially important, as there is no connection between them in terms of plot or characters. Instead, the link between them is thematic, as each is set in a period of Italy's past and uses fantasy to explore the society found in that time.
In the Cloven Viscount, the eponymous nobleman Medardo of Terralba is cut in half by a cannonball. His two sides both live, with his right side encompassing all of the Viscount's evil, and the left side all of his good. Medardo's nephew narrates the story, but he remains so firmly in the background that you often forget he is a character.
The story reads as a parable, eschewing realism in favor of archetypes. The characters aren't psychologically complex, but the structure of the story is such that this feels like a deliberate choice and not a weakness. It reads a little like a fairy tale, in that the characters aren't meant to be seen as actual people, but rather as instruments to get at some deeper truth embedded in the story itself. The writing likewise reflects this approach, it simple eloquence belying its poetic richness and depth.
I adored The Baron in the Trees, and though Viscount didn't grip me with quite the same intensity, it was still excellent and encourages me to read the final book in the trilogy.