She works with Monet St. Croix for the first time. Their first mission does not go well and Siryn deals with the loss of her teammate, Darkstar. X-Factor Investigations Siryn leaves X-Corporation to become a member of X-Factor Investigations. As part of her initial duties for X-Factor Investigations, she investigates the murder of a woman who died in a movie star's penthouse, on behalf of the victim's sister. A rival firm, Singularity Investigations, represents the actor with Damian Tryp, Jr. as the defense counsel. Siryn and X-Factor Investigations manage to incriminate the star and thwart Singularity Investigation's assassination attempt on Rictor. Tryp Jr. later ambushes Siryn and beats her, leaving her to die in an alley. She is later found and taken hostage by a mentally ill former mutant only to be rescued by Rictor. While recovering from her injuries, Cyclops approaches Theresa and informs her Banshee has died. She goes into a state of denial, holding on to how many X-Men have been believed dead have returned alive. During the Superhuman Civil War, Theresa opposes the registration act and is tasked with contacting more high-profile superheroes about the Decimation. After speaking with Spider-Man, X-Factor gets into contact with Quicksilver and Cyclops' team of X-Men, demanding they answer why the reason behind the Decimation was kept secret and defy the registration act. Siryn's relationships with Multiple Man and Monet become strained. After spending a night drinking, Madrox awakens to learn that he and one of his duplicates slept with Theresa and Monet. Although he is initially uncertain as to which was which, he concludes with near certainty that he slept with Theresa, and the dupe slept with Monet, though this does little to assuage Theresa and Monet's anger. Theresa resolves her differences with both Madrox and Monet, and the two women develop a budding friendship after a shopping trip to Paris and partner together on later missions. Siryn and Monet are sent to retrieve two famous child singers (who specialize in mutant hate songs) from their parents. The two are ambushed, knocked out, and kidnapped by the children's mutant bodyguards, Solo and Clay. They awake imprisoned, but they both escape and return the children to their grandparents. It is revealed that the entire mission was a ruse by Josef Huber to lure the women away from their X-Factor teammates, as both Monet and Siryn's mental-based powers negatively affect Huber's mind-control