Julie Power quit being Lightspeed during the Regent's rise to power. When either she or her sister, Katie, accidentally used their powers in school, the Power Pack came back into action. While on the run, the Power Pack was found and recruited into S.H.I.E.L.D..
Powers and Abilities
She appears to be the same age as her Earth-616 counterpart was upon receiving her powers, however that would mean that she did not receive her powers until Regent had already started hunting down superheroes.