Michael Zévaco's The Pardaillan Volume VI "Fausta's Wrath"

Synopsis

Fausta was an Italian Princess, who had love affairs with the rich and powerful. One of her lovers was a Cardinal, and convinced her to come to a secret conclave of Cardinals where she was elected Popess. Her Paris' palace was discretely connected to an inn where she hosted bacchanals and orgies incognito with the Parisian high society, only to blackmail them later. Violet was born from Eleanor, a protestant, whose Catholic lover abandoned her. She discovered that the bishop celebrating mass at Our Lady was him, and confronted him during the Eucharist ritual.