At 15, Joseph is the oldest resident of Little Lamplight. Perhaps as a result of his age (or the fact that he'll have to leave soon), he has taken it upon himself to hold classes to educate other Lamplighters, covering whatever he feels they need to know (or whatever they show interest in). When not occupied teaching, he spends his time working on his computer or researching old textbooks that were long ago scavenged from Vault 87.
Picking Up the Trail: If you speak to Mayor MacCready about another way into Vault 87, you can seek out Joseph and ask him about an old access door controlled by a "broken" computer. Joseph will turn on a hackable computer terminal that can open the door.
Joseph is the town barber and can give the player a change of hairstyle.
The player can sit in on Joseph's class by visiting the Little Lamplight schoolhouse in the mornings. If pressed during conversation, Joseph explains that he and his predecessors began by teaching survival skills to younger children. They were able to recover some holodisks from Vault 87's classroom at some point, but this provided them limited teaching materials. Over time, all access was cut off from Vault 87, and nothing new has been recovered in several generations.
PC If one convinces the other two children to leave Penny behind during Rescue from Paradise, Joseph will still act as though you saved her despite the fact that she remains in Paradise Falls indefinitely. [verified]
PC If one talks to Joseph about turning on the terminal while in the room containing Eclair's cafe it is possible for Joseph to fall in the water when he leads you to the terminal. This can be solved by leaving Little Lamplight, waiting 24 hours, and returning. [verified]