Help me find a book title.

Ok now that the OG fixed itself....

 

 

 

 

So my father inlaw swears he read a book when he was in the Romanian Military about a Pope that had an illegitimate son who becomes a pirate. Says it's the best book he ever read. I have looked for about 5 years, never finding anything.....

 

 

So I have come to the OG saviors

holy shit don't know but please post if you find out

don't know if this will help:
http://listverse.com/2016/07/18/10-fascinating-bastard-children-of-popes/

Sounds like the plot for Pirates of the Caribbean 6