The scion of an illustrious family from the Kingdom of Sicily and educated at Paris, he became known in Rome as a friend of the French church and of the Holy Roman Emperor.
It may have been the cardinal's brother, Manso, who received the royal baths at Amalfi from King Frederick II in 1205 and is known from documents between 1180 and 1213.
When his uncle came to France on official business in 1198, he secured for Peter canonries in the cathedrals of Paris and Sens and a benefice from the abbey of Saint Martin at Tours to support him in his studies.
The first takes as its starting point the first verse of Obadiah and, using crusade imagery, urges the audience to heed Christ's summons to battle sin.
[6] After his ascension to the papacy in 1216, Honorius III began a correspondence with Peter, making him one of the most famous Parisian professors.
[7] In the letter announcing his appointment, Honorius praised him as "a man greatly esteemed for his knowledge, character and reputation.
He was probably one of the advisors behind the pope's constitution Super speculam, issued 16 November, which forbade the teaching of law at the University of Paris.
In 1225, ambassadors from England approached a group of cardinals including Peter in order to draw the pope's attention to the ongoing Anglo-French conflict.
In 1228, he was a member of the committee of cardinals that examined Walter d'Eynsham, found him theologically unfit and recommended Pope Gregory IX quash his election as archbishop of Canterbury.
[9] In 1232–1233, Peter successfully petitioned the general chapter of the Cistercians to convert San Pietro della Canonica from a priory into a full abbey under the authority of Fossanova.