Fate/Zero is a four volume light novel written by Urobuchi Gen.
There’s a 25 episode anime adaptation, which I watched before reading. The novels are far superior, as we actually get to see character’s inner monologues, which is a huge, huge part of characterization. Kiritsugu feels a lot more human in the novels, though I still don’t like him very much hehe.
I had no prior exposure to the Fate series but, since Fate Zero is a prequel, it wasn’t necessary to have understood the universe. The first episode/volume gives a lot of background information on the Holy Grail Wars –maybe a bit too much overload.
I enjoyed the series largely anyway. With a large cast there has to be at least one character you’ll like (and loads you’ll hate)! 😀
I’m really amazed at how authors can weave so many characters into a series, creating distinct personalities, a plot that involves them all -and actually having that make sense. And also how they can make their own characters suffer so much. Yeah, Urobuchi, I’m talking about all your characters.