He gives the Initiate a discount when he kills all the radscorpions in the Carbon Warehouse. He appears on the street first but later moves into the warehouse to hide from raiders, like all the others. He had some trading agreements with the raiders, so he was able to move into their base, and he later helps the Initiate takedown Jane, the raider matron.
↑Fallout: Brotherhood of Steel Manual p.32: "Jesse Jesse’s an honest, down-to-earth fellow who’s fed up with raiders, with ghouls, with radiation, with, well, just about everything. A small-town trader who operates out of a an old ice-cream truck hitched to a pair of two headed cows who has little love for the various criminals that crawl across the wastelands but is more than willing to help you out, even lowering his down-to-earth prices."