Background: Mystique (Raven Darkholme) is a fictional character appearing in American comic books published by Marvel Comics, commonly in association with the X-Men. Created by artist David Cockrum and writer Chris Claremont, she first appeared in the comic book Ms. Marvel #16, published in 1978. Mystique is a member of a subspecies of humanity known as mutants, who are born with superhuman abilities. Mystique is a shapeshifter who can mimic the appearance and voice of any person with exquisite precision, and her natural appearance includes blue skin and yellow eyes.
Context: Mystique becomes the adoptive mother of the four-year-old girl Rogue. Rogue had run away from her home in rural Caldecott County, Mississippi. The girl was living alone in a wooded area, brandishing a shotgun and trusting no one, when Mystique found her. Destiny foresees that Rogue will be important to them and Mystique seeks her out, gains her trust, and takes her in. She and Destiny raise the girl, and Mystique grows to be very protective of her. Mystique, as Raven Darkholme, rises rapidly through the United States Civil Service to the trusted position of Deputy Director of the Defense Advanced Research Projects Agency (DARPA) in the United States Department of Defense. This position gives her access to military secrets and advanced weaponry, both of which she uses for her own criminal and subversive purposes. In this position, she attempts the theft of the Centurion weaponry from S.H.I.E.L.D. She also beat Ms. Marvel's lover Michael Barnett to death, and sought to kill Ms. Marvel. To help her in her criminal activities, Mystique organizes her own incarnation of the Brotherhood of Evil Mutants, consisting of herself, Avalanche, the Blob, Destiny, and Pyro. The Brotherhood attempts to assassinate Senator Robert Kelly, a notoriously anti-mutant politician. The X-Men thwart the assassination attempt, and all of the Brotherhood save Mystique herself are incarcerated. Rogue is trained by Mystique and eventually joins the Brotherhood of Evil Mutants. Her mutant power is the ability to absorb the memories, personality, and skills or powers of whomever she touches. To free the other members of the Brotherhood, Mystique concocts a plan involving Rogue absorbing the powers of Ms. Marvel and the Avengers. Though the plan is successful, the Avengers ultimately defeat the Brotherhood of Evil Mutants, capturing all of them except Rogue and Mystique. Moreover, Rogue finds that she has absorbed Ms. Marvel's memories, personality, and powers permanently. In a further humiliation, a confrontation at the Pentagon ends with Mystique being defeated and turned over to the authorities by a powerless Ms. Marvel. The Brotherhood of Evil Mutants eventually escape, and battle against Dazzler. In an act of revenge against Mystique, Mastermind unbalances Rogue's psyche with the one she absorbed from Ms. Marvel, which prompts her to defect to the X-Men. Because Rogue left without a word, Mystique assumes that Professor X, the X-Men's mentor, brainwashed her. The Brotherhood of Evil Mutants accordingly launches an attempt to kill Professor X. Rogue stops Mystique, and explains that she joined the X-Men because Professor X, as the world's most powerful telepath, is her best hope of healing for her fragmented psyche. Mystique reluctantly relinquishes her guardianship of Rogue. Anti-mutant sentiment rises and the federal government launches its own covert anti-mutant program, Project Wideawake. Believing that the times have become too dangerous for the Brotherhood of Evil Mutants to continue, Mystique goes to Doctor Valerie Cooper, special assistant to the head of the National Security Council, and offers the Brotherhood's services to the government. In return for entering government service, Mystique and her team receive a presidential pardon for all criminal charges, to be revoked if any member of Freedom Force is found committing a crime. Cooper agrees to convey the offer to the President on the condition that the Brotherhood arrests their founder, Magneto. The Brotherhood, now reincarnated as Freedom Force, are defeated by Magneto and the X-Men. When Magneto learns that Freedom Force are official federal agents, he voluntarily surrenders to them. Mystique leads Freedom Force in capturing the Avengers on behalf of the federal government. She clashes with X-Factor in seeking to arrest Rusty Collins. With Freedom Force, she fights the X-Men in Dallas, and witnesses her foster daughter's apparent demise. With Freedom Force, she battles Cyclops and Marvel Girl. With Freedom Force she seeks to arrest Rusty Collins again, and battles the New Mutants. She finally succeeds in capturing Collins as well as Skids. She leads Freedom Force against the Reavers on Muir Island. On this particularly disastrous mission, Freedom Force loses two of its members, Stonewall and Mystique's lover Destiny. The death of her lover leaves Mystique psychologically scarred. Mystique is later nearly killed by Dr. Valerie Cooper, who is under the Shadow King's mental control. She then impersonates Dr. Valerie Cooper. Mystique is eventually discovered impersonating Dr. Cooper, and saves Xavier's life by killing the Shadow King's human host, Jacob Reisz. She finally reconciles with Rogue. In time, she comes to terms with Destiny's death. She teams with Spiral and Wolverine in thwarting Mojo's near-destruction of the universe. Mystique later briefly stays as a guest at Xavier's mansion. She begins going insane, and leaves the mansion under the care of Forge. Professor X is forced to make Mystique his secret agent, as his previous one, Prudence Leighton, has died and Mystique is the only one suitable to complete the missions. Xavier poses as Magneto to rescue Mystique from the Department of Homeland Security and from execution at the hands of Johny Kitano, Special Magistrate for Homo Superior crimes against humanity, and a mutant himself. At this time, Mystique claims that there is an imposter out to frame her, taking control over the Brotherhood and sending them on their recent missions (the assassination of Moira and the infiltration of X-Corps). As long as Mystique completes the missions without killing anybody, Xavier keeps her safe from the authorities, who are out to execute her. Working with Xavier is Forge. One of Xavier's enemies, the Quiet Man, who is actually Prudence Leighton inhabiting the body of her assassin, contacts Mystique and offers to give her an interference transmitter which would keep her safe from the authorities if she kills Xavier. Creating a plan that would free her from both men, Mystique pretends to try killing Xavier while secretly working with the mutant thief Fantomex, after alerting Forge to stop her at the last moment. Her plan is to have the Quiet Man see this and believe that she really has attempted to kill Xavier and is still working for him. The other X-Men believe that Mystique has tried killing Xavier and seek her out. Rogue tracks her down. Distraught with rage, she attacks her foster mother. Mystique escapes by blowing up the house and going through the window, changing her form to shield her fall. Mystique goes to the Quiet Man, who is planning on having her killed. After a battle, Mystique kills the Quiet Man, saves her former field-handler Shortpack, and discovers the Quiet Man's interference transmitter was a fake. She tries to steal Forge's interference transmitter but is caught. After some angry words, he smashes it and tells her he never wants to see her again. The two share a sad goodbye kiss and Mystique leaves. After Mystique is gone, Forge realizes that she had already switched his transmitter for the fake one. CANNOTANSWER
Question: Who did she turn on to become a double agent?. Whats the answer?

United States Civil Service