Sara Hingle was just a normal girl who went to school with May Parker ( Spider-Girl), who began to experience terrible migraines. She thought she just needed aspirin. But then she manifested mutant powers and the resulting energy blast was destructive. With the entire school knowing about her mutancy Sara felt horribly alone, but began to suspect that May was a mutant and tried to follow her, only to be attacked by Humanity Firsts, an anti-mutant hate group. Two mutants named Impact and Pirouette attack the group violently and May had to save them as Spider-Girl. Impact and Pirouette convinced Sara to meet their other member, a young girl with an enormous head and telepathy named Headcase. They gave Sara a costume and codenamed her Nucleus and convinced her to join them. Nucleus met the teams leader, Magneta, who influenced Nucleus into thinking that humans were the enemies of all mutants. She attacked the Humanity First headquarters with her explosive mutant powers and attacked Spider-Girl thinking she was a member of the hate group since she saved them from Impact and Pirouette. Spider-Girl had to resort to physical force and attacked her friend. Spider-Girl had Push try to convince Sara to join the X-People. After a brief battle with Spider-Girl and Push, Sara fled, not wanting to become some type of terrorist. Magneta was completely furious and used her magnetic powers to cause Sara to go into "meltdown" creating an almost atomic blast, destroying everything in sight. She survived but was left in a coma as a result of her powers going into meltdown.
Energy Blast: Nucleus can fire explosive blasts of energy from her body that manifest as a series of rings, similar in appearance to the atomic symbol. These blasts strike and object with intense heat and concussive force