José was the 'uncle' of Dan Cahill and Amy Cahill.
José was a patron at Grace Cahill's week-long winter holiday at the Cahill manor. He went to her funeral, putting a shovel of dirt on Grace's grave, and was invited to her will reading. William McIntyre showed a video of Grace explaining the rich Cahill heritage, amazing José. However, when offered to hunt for 39 Clues or take a million dollars, José easily took the million, and left.