Nothing much is known about the mutant known as Headcase. She is part of a small group of extremist mutants who believe in fighting against hate groups and anti-mutant groups through what ever way possible. Headcase possesses high levels of telepathy and due to her powers, her head is large but her body is small like a doll. After Pirouette and Impact rescued Sara Hingle from a group of kids that belonged to Humanity First. Spider-girl ended up protecting the group from both Impact and Pirouette, leaving Sara to see that Spider-girl was more towards hating mutants than helping them. Sara joined both Pirouette and Impact to their base and met the mutant, Headcase, who revealed that Sara had been followed. They attack both Spider-girl and Moose Maxfield and in the resulting battle, Headcase, Pirouette and Impact fled with Sara left injured in Moose's arms. She later regrouped with Impact and Pirouette and introduced Sara and her mother to their leader, Magneta. After a brief battle with Spider-girl and Push, Sara and her mother fled from the Sisterhood of Mutants. However, Magneta finally convinced Sara to attack Humanity First but as her powers went out of control. Spider-Girl talked Sara down before he murdered everyone in the building. Magneta completely furious used her magnetic powers to cause Sara to go into "meltdown" creating an almost atomic blast, destroying everything in sight.