The legend conserved in the Atti Bolognesi states that during the persecutions carried out by Diocletian, Januarius, bishop of Benevento, escaped from his see and traveled to Pozzuoli "incognito." However, his presence became known to Christians in the area, and Januarius maintained contact with a deacon of Miseno, Sossius, as well as the deacon Festus and the lector Desiderius.

Sossius was soon discovered to be a Christian by the local authorities and he was condemned by the judge Dragontius, who condemned him to be killed by wild bears in the local amphitheater. Januarius, Festus, and Desiderius, on hearing of Sossius’ arrest, took a risk and visited him in prison at the sulphur mines of Pozzuoli, near the volcano of Solfatara.