Sarah was the only child of a single father. Her father, a mechanic , owned an auto repair shop, and also worked with tech heroes who didn't have the knowledge, time, or tools to repair and maintain their own equipment.
From time to time (and more frequently as she grew older), her father would bring Sarah in to work with him in lieu of daycare or a babysitter. During one of these days, they discovered that she not only enjoyed working with machines, but also possessed a preternatural understanding of their workings. As she grew older, so too did her talent with and understanding of machines grow, and she had many opportunities to observe the strange and occasionally 'impossible' machines from their 'special clients'.
Alas, it was not to last. One unfortunate day, the building collapsed, killing her father and trapping Sarah inside. Fortunately, a hero was on his way to get the oil changed in his battle suit, and was able to rescue her from the rubble and rush her to the hospital. Amputations were made due to infection, and after she had made as much of a recovery as was possible, she was remanded into the care of the State Home for Displaced Youngsters.
Sarah had not been particularly outgoing before, and her recent experience led her to withdraw even further, only comfortable enough to open up when allowed to work with machines. It was at this time that she also made her first invention: simple cybernetic replacements for the hospital prosthetics.
Safety regulations, however, prohibited her from keeping mechanical equipment, and the cybernetics were confiscated. One of the state employees at the Home took a special interest in Sarah's situation and contacted The Academy for Super-powered Youths, believing that the Academy would be better suited for Sarah's well-being.