Fortunatus was patriarch of Grado for a few months, between 627 and 628. The Cronica de singulis patriarchis Nove Aquileie specifies that Fortunatus had denied the faith ratified by the Council of Constantinople in 553 and had passed to the Three-Chapter party. After his adherence to the schism, he had robbed both the Church of Grado and the churches and hospitals of the Istrian province of their treasures (“in auro et vestibus vel ornamento”), and had eventually escaped into Lombard territory, in the castle of Cormons. These circumstances, about his schismatic position, robbery and escape, can be also found in the letter sent by Honorius I, where the pope wrote to his addressees that he had sent legates to the Lombard king Arioald with the firm demand to persecute Fortunatus and claim the purloined treasures. His destiny in Lombard territory remains obscure.