Spoiler Warning:Plot and/or ending details are in the text which follows.
Karen is an undercover government official who works for U.L. Paper. Before her identity is revealed, she becomes Niko's girlfriend under the false name Michelle.
After unveiling her identity, she confiscates Elizabeta's cocaine, and can no longer be dated. She is a smoker and may have a criminal past, as hinted by the boss at U.L. Paper. She claims to work with Mallorie.This is false information as Mallorie only works in Roman's Cab Depot and is truly lying.
It is unknown when Michelle got assigned Niko's case. There is evidence that it is from the start of the game, as she is already lying to Niko.
During a mission for U.L. Paper, Niko asked about Michelle, to which he is replied with "Michelle,Karen."
Michelle/Karen in the mission first dateTruth of real identity
Karen says that she works with Mallorie Bardas,However,Mallorie only works at Roman's depot.
Karen asks Niko for drugs.
Asks if Niko and Roman are involved with the thugs.
If you fail the mission First Date by attacking her,She says that Niko is involved with the thugs in hove beach.
