Yes! He's a villain in the series but he's great fun. He's in both TV show and movie; book-Gerb is closer to his historical counterpart with more of an interest in science, but he gets a lot more scenes politicking about in the TV show (he's supporting castin the book, but absolutely a main character on the TV show). The author really likes the Auvergne-Rhône-Alpes region and from what I remember of the books there's a considerable amount of the books/show is set there.

I also discovered - literally today! - that he is the main character in Judith Tarr's Ars Magica where it looks like he's the hero in that one. Just got it today so I am hoping it's a good read!

I'm glad I'm not the only one with an interest in medieval popes. :) But man, this dude had an interesting life!