Welcome to the big house, Francis!
I'm a big fan of the Papacy both in real life and in fiction. I've read a lot of stories and novels based on the Papacy, and can say that of all the books out there, we can say we have three Papal novels with pretty good track records:
Morris West's The Shoes of the Fisherman - E European Pope
Morris West's The Clowns of God - Pope resigns
Walter Murphy's The Vicar of Christ - Papa Francesco I......
All three are brilliant and partially prophetic.
THE SHOES OF THE FISHERMAN was a brilliant speculation on the Papacy and the effect of an Eastern European Pope--enormously influential in the story; even more so in real life.
THE CLOWNS OF GOD tell the story of Pope Gregory XVII--a French survivor of WW2 who resigns the Papacy: although the plot of the story is fictional, there are strong parallels between Gregory and Benedict XVI, a German survivor of WW2 who has resigned the Papacy for mysterious reasons of his own.
Then there is.... VICAR OF CHRIST, which is one of my favorite novels, now, alas, dated by its late 1970s origins, ...but is an excellent overview of what would happen if Walter Murphy (the author of the novel) had become Pope after serving in the Marine Corps and in the Supreme Court of the United States. Excellent read, entertaining, but, um, a bit too much of what tvtropes.org calls "Author Avatar." I do like how its three narraitors have such radically different 'voices'--one a Marine Gunnery Sergeant (kinda like a Battalion Sergeant Major), one a Supreme Court justice, and one a highly intelligent but highly corpulent gourmand of a Cardinal--who each describe Declan Walsh's journey from soldier (hokay, Marine) to almost-saint. The description of Marine service, Court workings and the Vatican are keenly carved. Good stuff.
It's highly unlikely THIS Francis will be anything like the one in Vicar of Christ... but yanno... It's a strange world after all.