Cypher isn't a member of the Brotherhood, but he is sponsored by them in exchange for information. Cypher is a greasy, shifty-eye looking character who fits in well with any bandit or raider camp. He has a knack for blending into the crowd as long as they are bloodthirsty marauders. Taking the average wastelander into account, Cypher is practically invisible.
"That was too close. I thought I was going to have to cap your ass, since you almost blew my cover. Well, anyway, as long as I get paid, I can party with full afterburners on...you know what I mean?"
It seems likely Cypher is a reference to his namesake in the first Matrix movie - (Lu-)Cypher is a spy and a traitor working for the Agents to bring down the Matrix hackers, and almost succeeds.
