The books are terrible! Don't be tempted to read them (I was, obviously). Almost everything that's good about the show comes from the script writer and the actors.

I don't know much about Robert Runcie, but I do think it's weird that James Runcie based his hero on his father. It explains, among other things, why Sidney comes off (in the books) as so desexualized.

I don't know if there's fic yet. I've got ideas but I want to wait until the current series is over.