Michael C. Vaughn is a fictional character played by Michael Vartan. He is one of Sydney Bristow's co-workers and ongoing love interest on the television series Alias. He, like Sydney, is talented in a variety of areas. His language skills, shown in various episodes, include French, Spanish, Italian, and others. Throughout the series for the first 3 seasons his code name was boyscout and as of season 4 his code name was shotgun.
Michael Vaughn was originally Sydney Bristow's handler while she was working as a double agent for the CIA within SD-6. But gradually, the two agents developed romantic feelings for each other as they worked closely together to bring down this corrupt espionage organization. This did little to endear him to Sydney's father Jack Bristow, another double agent within SD-6. Vaughn and Sydney's relationship became openly intimate after SD-6 was destroyed during the show's second season. When Sydney was apparently killed in a fire a few months later, a heartbroken Vaughn left the CIA and found work as a French teacher. He also became involved with NSC liaison Lauren Reed and married her some time during Sydney's two-year disappearance. Once he discovered that Sydney was still alive, Vaughn returned to the CIA and quickly saw his feelings for her reignite, a fact that caused a great deal of tension in his marriage to Lauren. Eventually, it was revealed that Lauren was a double agent for The Covenant and that Lauren seduced him in order to gain information on Sydney. Vaughn became obsessed with her capture and was encouraged by Jack Bristow to kill her, which he did at the end of the third season. This act continued to haunt him into the fourth season even though he shot Lauren in order to prevent her from killing Sydney.
Following Lauren's demise (and between the third and fourth seasons), Vaughn appeared to go into an emotional tailspin that culminated with him setting fire to his own house. He went through a month of psych evaluations before informing his best friend and fellow agent Eric Weiss of his resignation from the CIA. In reality, Vaughn had been recruited into a black ops division of the CIA called Authorized Personnel Only (APO), along with Sydney, Jack, and Marcus Dixon (Weiss and Marshall Flinkman would soon follow). One of his new duties was to keep an eye on Arvin Sloane, who had been appointed director of APO despite his long history of criminal activities as the head of SD-6. Vaughn successfully resumed his romantic relationship with Sydney during their first mission for APO.