Jiggs as he appears in the Prima Guide
Jiggs is the partner of Prime, a suggested pair of scavengers or possibly raiders, though due to the manner of dress and demeanor in which Prime communicates, the former is more so implied than the latter. Notes addressed to him can be found in the Museum of Technology as part of the unmarked quest Jiggs' Loot.
Two hackers were attempting to divide some loot spoils, and Jiggs never made it out of the Museum of Technology alive, or survived long enough to solve a riddle Prime posed for him.
Jiggs is mentioned in Fallout 3 but does not actually appear in the game.