This wandering merchant sells a variety of junk, equipment, and weaponry, but also dabbles in scavenging and selling robot parts. He's built a good rapport with wastelanders, and Sheriff Simms of Megaton is particularly happy with his purchase of Deputies Steel and Weld. He can currently be seen wandering the wastes with his robotic entourage, which includes an old Mister Gutsyarmy unit named Sergeant RL-3.
Joe sells Sergeant RL-3, a robot companion, for the price of 1000 bottle caps (500 with a passed barter check) if the player has a neutral Karma. If he is dead you will not be able to acquire Sergeant RL-3.
Sometimes after the player has bought Sergeant RL-3 and choosing him as a follower, Tinker Joe and his protectron will randomly spawn with you after fast travel or entering a location then run away, most of the time resulting in his death.
After reverse pickpocketing items onto Tinker Joe it may take up to three days before he'll equip the new items; entering and exiting nearby locations such as the RobCo Facility or Tenpenny Tower will not speed the process.
He will sometimes equip gear that you sell him, such as raider armor.
Tinker Joe refuses to sell Sergeant RL-3 to you unless you have neutral Karma saying that he "doesn't like the look of you".
If you wish to purchase the RL-3 bot, you must do it as soon as possible..... occasionally Tinker Joe will run into yao guai and 90% of the time will fail to defeat it and perish. At times, he does defeat the yao guai, only to lose his protectron and Mister Handy he was apparently delivering to a client, even though he patrols around the RobCo Facility. These yao guai often spawn in the path of Tinker Joe in a trailer just south of Tenpenny Tower.
Tinker Joe says the other two robots are reserved for delivery, but he never leaves the vicinity of the Robco Facility.