Berrigan sometimes works undercover for the Ranger Corps, something which Will eventually guesses in The Sorcerer in the North; however, he mainly earns his living as a jongleur. In the fifth book, he teaches Will how to be a jongleur with his mandola in order to have cover in Macindaw, and travels with him part of the way. Will later uses the skills Berrigan taught him while he is in Norgate Fief.
He plays a gitarra, the equivalent of a guitar, and is said to be very good at it; he also has a fine singing voice, often entertaining the Rangers at Gatherings with Will occasionally accompanying him on his mandola. His jongleur cloak is patterned similarly to a ranger camouflage cloak, though it is more brightly colored.
He is also mentioned in The Tournament at Gorlan, where he joined Crowley, Halt and Leander. He was said to have created the Ranger Song 'Cabin in the Trees'. He was to be taken by Willet, on charges of 'treasonous talk' (referring to his singing of 'Old King Artur, the Terrible Farter'.