The Translation of Father Torturo, by Brendan Connell
One of the best works of fiction in the English language is Hadrian the Seventh, by Frederick Rolfe. It is shameful that it is so little-known. Connell therefore gets off to a great start when he dedicates this book to Rolfe "for the design which I so meanly twisted". In both books, a priest of somewhat dubious antecedents is catapulted into the papacy, embarks on a whirlwind of reform, and is ultimately offed. But that's about as far as the parallels go.
Connell's Xaviero Torturo is a nasty piece of work. A bully as a child, but highly intellectual, he is mentored by a village priest who is himself somewhat dodgy - they both dabble in the occult and, in Torturo's case, in "black magic". Torturo is also a thief, a blackmailer, and he has at least four people killed, and may have killed two more himself. Rolfe's priest, George Arthur Rose is instead a paragon of virtue who merely wants to be a priest and finds his ascent to the throne of Peter to be baffling.
Both, however, are quite competent popes - both spark something of a revival of catholicism, Rose by his piety and actually bothering to live by what it says in the bible, Torturo by fake "miracles". And both works - and both fictional popes - are scathing about the corruption both personal and institutional that is the Roman church. Torturo is, of course, happy to use that corruption for his own ends but is at least honest enough to see it as hypocritical. And finally, both fictional popes have mercifully (for the rest of the Roman hierarchy!) short reigns. Rose falls to an assassin opposed to catholicism, whereas Torturo's crimes eventually catch up with him.
Torturo actually survives, being merely thought to be dead, and there are all kinds of delicious possibilities for the way things could continue after the book ends. Normally when this sort of thing happens, I am left shouting at the author "for god's sake learn to write an ending" but in this case, no. Things are tied up neatly, and yet the reader is still left to think for himself. And therefore I whole-heartedly recommend this book.