Born in May of 1080 Cadfael initially did not see the religious life as a possible occupation. He was a worldly man, having served as a soldier in the First Crusade under the command of Robert Curthose. After Jerusalem fell to the crusaders Cadfael lived several years in Syria and the Holy Land. During that time he had a son by a young Syrian widow named Miriam, and earned a living as a sailor.
Upon returning to England in 1114 Cadfael became a foot soldier in King Henry's war to ensure union with Normandy, followed by service in England to Roger Mauduit. After rescuing Prior Heribert of Shrewsbury Abbey he was released from Mauduit's service. Tired of a life of violence he accompanied Heribert back to the abbey and soon became a monk in the abbey.
As a monk Cadfael put his knowledge of herbs to good use, coming up with concoctions that could at least ease the pain of the sick, if not cure them. Due to his abilities Cadfael was able to frequently travel beyond the confines of the abbey and help the people of the surrounding community. He was a very observant man, able to piece together clues to a puzzle that solved crimes and various other mysteries.
Cadfael did not often preach to others, preferring to instead perform corporal works of mercy and acting as a good example to others. Not being a priest he was unable to hear confession or perform other duties reserved to priests, but he always had time to listen to people who wanted to talk to him. Having entered the monastery later in life he had knowledge of the secular world that some of his brothers lacked. This secular knowledge he possessed gave him an empathy for people outside the abbey and their daily struggles.
During the course of the series Cadfael became good friends with Hugh Beringar, who was the Deputy Sheriff and subsequently Sheriff of Shropshire. He worked with Beringar quite closely to solve crimes that happened in the area.