He makes appearances in the Quest del Saint Graal section of the Lancelot-Grail cycle, but his story is fully told in the Estoire del Saint Grail (History of the Holy Grail), a prequel section written somewhat later.
Josephus is considered the primary holy man of the group, which is in contrast with the Lancelot-Grail's major source, Robert de Boron's Joseph d'Arimathie [fr], in which his father is the undisputed leader.
This is likely due to the authors' assertion that various great families are descended from Joseph; his virtuous son remains chaste and has no children.
[citation needed] When Joseph's followers reach Britain, Josephus becomes the island's spiritual leader while his brother Galahad (ancestor to the more famous knight Galahad) takes charge of the secular duties.
Before he dies, Josephus passes the Grail to his nephew Alan and announces the quest for the object that will eventually preoccupy King Arthur and his court.