- "Blessings on you, brother."
- ―Darby to Ezio after being rescued, 1494.[src]
After Darby's Gaelic father married a Catholic woman, he was not allowed to raid and had to work the fields. To escape his father, Darby decided to become a monk, encouraged by the belief told by his mother that monks "did little work, and threw large feasts for the seasonal holidays."
Travelling to Italy
Darby joined the Abbeylara Monastery in 1462, and became a Cistercian. Ultimately, however, he found the Order too austere as he and the monks had to work in the fields from dawn until dusk and the Abbot Shaw did now allow the monks to drink, with the only girls being nuns.
Convincing a small group of his fellow monks to join the Dominicans, Darby left Ireland in 1463 for Italy. Ultimately, Darby was kicked out of the Dominican order in 1493, due to his repeated attempts to convert townspeople while within a drinking house.
Probably during the same year or shortly after, Darby was attacked by a group of soldiers. Luckily for him, Ezio Auditore da Firenze was nearby and saved him from his attackers. Ezio asked him if he knew of a monk with a missing finger, to which Darby recalled seeing the man in the abbey of Forlì.
Darby died in 1500 from what was described to be "bad blood", but was most likely syphilis. His body was buried in the small cemetery beside his church.
- "O'Callahan" is an anglicized version of the Irish name "Ó Ceileacháin", which means "descendant of Ceallacán".