Sister

is a man found in Rivet City. He is an unapologetic Slaver, and is in the city to re-capture an escaped slave, Mei Wong. Conversation with him is less than verbose: he has a simple goal and wants to discuss nothing but that.

If asked about his name, Sister will refuse to go into further detail. In his room is a recording pertaining to the quest The Replicated Man, concerning the Slavers' desire to enslave some androids.

Unmarked quest: Slave Hunt
When you first meet Mei Wong she seems very scared because she is afraid of Sister. You can help either Mei Wong or the slaver and receive good or bad Karma based on your actions.

A few days after making your decision, Sister will disappear from Rivet City, ostensibly either to return the slave to Paradise Falls or because he has fled or was killed.

Appearances
only appears in Fallout 3.