The eldest child of a wealthy ambassador, mutant Monet St. Croix was a spoiled, pompous girl. After her brother Marius, a student of dark magic, invited her to join him in world conquest, she scornfully rejected him. For this, Marius magically trapped her in the form of a red-skinned mute dubbed Penance. Believing their brother had killed Monet, her young twin sisters banished Marius to another dimension. Seeing Marius as the only way to return to normal, Monet followed. To spare their father from a broken heart at the loss of his favored daughter, the twins used their powers to merge with each other into a single being that duplicated Monet mentally and physically. As Monet, the twins were among those mutants captured by the techno-organic alien Phalanx race, who sought to assimilate mutants into their collective. The twins and their fellow prisoners were rescued by an ad-hoc X-Men team led by Banshee, and they went on to join Generation X, a team of trainee mutants at the Massachusetts Academy under co-headmasters Banshee and Emma Frost. Meanwhile, after years of imprisonment during which Marius – now calling himself Emplate – used her as a source of sustenance for his energy-draining powers, Monet escaped to Earth. She was found by the Australian aboriginal mutant Gateway, who had been mentoring the twins, and he took her to the Massachusetts Academy. Initially distrustful, Monet soon accepted her new situation and ultimately joined the team.
Eventually, the twins’ true nature was revealed, and they soon after merged briefly with their brother, learning Monet’s true fate. They next merged with the Penance form, freeing Monet but becoming trapped in it themselves. During a subsequent battle, Jubilee defeated Emplate with an explosion that also freed the twins from the Penance form. Shortly thereafter, Monet’s father withdrew her from the Academy and took the sisters home. Monet was enrolled in a private boarding school in the Swiss Alps, where she soon discovered the headmaster was secretly a vampire feeding on students. Defeating him, Monet returned to the Massachusetts Academy and romanced her teammate Everett Thomas (Synch), who was ultimately killed by a bomb planted by Emma’s sister, Adrienne. The students soon quit, and the Academy closed. Monet and her former teammates Husk and Jubilee joined Banshee’s paramilitary X-Corps. Monet stayed on after the X-Corps was restructured into the X-Corporation, and also aided the X-Men’s Juggernaut against Black Tom Cassidy. Following the X-Corporation’s closure, Monet joined the staff of the mutant detective agency X-Factor Investigations.