She first appears when directed by Professor Selzer to collect Wesley Gibson and bring him to the Fraternity. With a fake smile on her face (as highlighted by her extremely crude word choices) and several of her bullets unloaded into the innocent civilians around her, the Fox collects Wesley and brings him to the Fraternity headquarters. Prompted by Selzer, she brings out Wesley's talent with guns by threatening to shoot him unless he shoots off the wings of a fly.
Overseeing his training, The Fox develops a relationship with Wesley and reveals to him that his father, the Killer, had been an associate of hers and that they had left the faction under Mr. Rictus due to an alleged disgust at Rictus' desire to kill children. Prompting Wesley further, he comes to the conclusion that Rictus is responsible for his father's murder. Wesley and the Fox dispatch most of the supervillains joining against the Fraternity following Selzer's murder and eventually Wesley kills Rictus much to the Fox's delight.
However, the Killer reveals himself to have set up the plot to make Wesley "tougher" with the help of the Fox who fed Wesley lies about their past. Following Wesley's murder of his father as per his command, The Fox joins him as a leading member.
Film VersionSimilar to the comic version, the Fox, played by Angelina Jolie, ushers Wesley into the world of assassins and death. Directed by Sloan, she leads Wesley to be trained so that he may join their ranks as an assassin. As a strict follower of the unusual Loom of Fate though, she is informed by the leader Sloan that she must kill Wesley as per his name appearing in the loom.
Traveling with him to seek out the bullet-maker Pewkarsky, The Fox then attempts to kill Wesley and the alleged killer Cross by crashing her car into the train carrying them. Once Cross reveals himself to be Wesley's father, confirmed by the Fox. However, she still tries to kill Wesley as per the Loom. Wesley escapes and is helped by Pewkarsky to recover. It is revealed during this time that Sloan has been lying when interpreting names once he saw his own in the fabric and sought to protect himself by delivering fake targets.
At the Fraternity headquarters, Sloan is exposed. To defend himself, Sloan states that he began interpreting fake names in the Loom of Doom so as to protect his fellow assassins in addition to himself. Being devout to the Loom, the Fox violently guns down the other assassins and ends her own life, throwing her gun at Wesley to stop him from saving her.