Pipboy (character)

PIPBoy is an actual person version of Vault Boy who could be encountered by the Warrior as a joke character. He may join the Brotherhood of Steel and fight as a squad member, but is not considered an official member by the Brotherhood due to not being a normal person (which in this case is to say he does not fit into any known species of the wasteland).

Background
While the existence of Vault Boy in the Fallout world as an actual person is obviously meant as a joke and Easter egg and not to be taken seriously, the most likely canonical explanation of this character is that he was some sort of robot or artificial human created by Vault-Tec who wandered off into the wasteland after the war. The fact the Brotherhood don't see him as a member could be explained by the fact he is a strange, never-seen-before creation, and they merely study him or use as a military device.

Availability
PIPBoy becomes available after you find him in the Pipboy special encounter. He joins the group when you speak with him if you have fewer than 5 members. He will go away and appear in the recruits pool if you have 5 members. If you have 6 members, he will do nothing.

He will join you even if you are lower level than he is when you discover him.

Attributes
He has a Perk Rate of 3 yet at the time he is discovered, he is level 8 with 3 perks. This is likely due to the fact that PIPBoy cannot change stance; by granting Flexible as a freebie, the player is protected from later wasting a gained perk on it.

He moves considerably slower than other characters when not in turn-based mode.

He has no biographical text in the character screen or in the recruitment pool.

Appearances
PIPBoy/Vault Boy as a person appears only in Fallout Tactics.