A post from 2012:
The Showtime Borgia series shows the pope's current mistress, Giulia Farnese, teaming up with his daughter Lucrezia and his former mistress Vanozza (Lucrezia's mother) to reform corruption among the cardinals of the Church. Did this happen?
Not a chance. It isn't even an accurate portrayal of these women, from what little we know of them.
About Vanozza we know this much: she was a former courtesan and the acknowledged mother of Juan, Cesare, Lucrezia and Gioffre Borgia, four of Alexander's nine acknowledged children. She had three husbands, all of whom were chosen by Alexander to help her become (semi) respectable. If she and Alexander still had a sexual relationship when Giulia was his mistress, they were very discreet about it. She did not maintain rooms in the papal palace, and certainly did not take care of the infant Giovanni Borgia, whom no one acknowledged as Lucrezia's child (and who may not have been Lucrezia's child–see my blog, "Lucrezia pregnant in a convent?"). There is no evidence that Vanozza was a social reformer.
Similarly, we know little about Giulia Farnese, except that she was barely older than Lucrezia, reputedly the most beautiful woman in Italy (known simply as "La Bella Giulia" or "La Bella"), and the mother of yet another of the pope's children, a girl named Laura.
Showtime has built up La Bella Giulia at the expense of Lucrezia. From what we know about Giulia, she was timid and flaky. She was not off rescuing Lucrezia, as showni in the Showtime series, but instead visitng a sick brother at the time of King Charles VIII's invasion of Italy. She ignored increasingly frantic orders from the pope to return and was captured by the French army when she tried to do so. (Contrary to Showtime, Lucrezia was safe in Rome at the time.) The French king was chivalrous enough to grant her safe conduct without even demanding a ransom. Given the atrocities his army was committing at the time, she was very lucky.
The experience evidently rattled Giulia, however, who fled with her child when the French army later approached Rome from the south after capturing Naples. Pope Alexander never saw her or Laura again. In other words, after the middle of Season 2, even Giulia's presence is fiction.
Showtime assigned character traits to Giulia that really belonged to Lucrezia, who was bright and educated. Lucrezia was fluent in Latin, judging by her library. When she was still in her early teens, Pope Alexander acknowledged her intelligence and judgment by having her painted as Saint Catherine of Antioch, dazzling the Byzantine Emperor with her knowledge and rhetorical skills. That's her above, wearing a turban and counting her arguments on her fingers, as Saint Catherine does in legend. Lucrezia is the center of this vast painting, a tremendous tribute. When she was older, Pope Alexander often had her sit with him when he held court, made her Governor of Spoleto (where she instituted various reforms), and even had her run the Vatican in his absence.
So if any of the of Borgia women could have reformed the corrupt cardinals, it would have been Lucrezia. But she didn't, nor did anyone else until Martin Luther got things started fourteen years after Alexander died. But that is another story