This article focuses on some crucial aspects of a satirical text of the sixteenth century, the "Diálogo entre Caronte y el ánima" de Pedro Luis Farnesio, which had a high circulation both in Italian and Spanish circles. The author of the dialogue, probably the diplomat Diego Hurtado de Mendoza, describes the conspiracy of Piacenza (1547) from an anti-farnesian and anti-papal point of view, setting it in a perspective of pro-imperial propaganda. This way opens up a new horizon and wanders from the local background, both politically and culturally. Therefore, we are in the middle of a debate on the theme of sovereignty and its possible degeneration into tyranny. The article gives a Machiavellian reading of the text, comparing extracts of the "Principe" and of the dialogue to analyze Pier Luigi Farnese's government action in a way which goes beyond the "topos" of the tyrant.