Callie Betto was a student at the Xavier Institute. When the students were placed on training squads, she became a member of Cyclops' Corsairs training squad. During her time at the Institute, Callie formed a friendship with Mercury.
After the events of the M-Day Callie was depowered. She was killed shortly thereafter when William Stryker fired a missile at the bus that she and most of the Institute's other depowered students were forced to board to leave the institute.