Delilah Deerborn - not your average physics major - was a student at Empire State University when she was involved in an accident with an experimental particle accelerator on campus. The surge of radiation gave Delilah the ability to copy any nearby superhuman being's powers derived from exposure to gamma radiation. Although some abilities can be beneficial, Delilah found out how detrimental hers can be. As a gamma powered serial killer ran rampant throughout the streets of New York, Delilah began having dreams of his exploits – dreams that were actually the killer's thoughts, and she was literally seeing events through his eyes. A sighting of the murderer brought the NYPD and their superhuman consultant, Doc Samson, to the scene. Samson tackled the suspect head-on and captured the supposed perp, but it turned out the prisoner was actually Delilah whose powers physically and mentally transformed her into the shape of the deranged killer, Patchwork.
Samson knew there was something more to his captive, and once he discovered her secret, he had her copy his gamma patterns in order to bring her to her senses. Now imbued with super strength, and the confidence to go with it, the young woman now dubbed Geiger was ready to help capture the actual Patchwork. Geiger became the best candidate to track Patchwork because she was still attuned to his gamma signature, but her inexperience almost led to an early retirement for both her and Samson. However, with the help of She-Hulk, Polaris, and some dumb luck, Patchwork's civilian identity was established, and he was soon brought into custody. Afterwards, Samson gave Geiger a lock of his hair to help keep her steady if she ever picked up any bad gamma signals.
Some time later, Geiger was considered to be a good recruit for the Initiative by Iron Man and was taken into the program. Alongside other trainees, Geiger was defeated at the hands of KIA, but she helped to battle the Skrulls during their attempted take over of Earth.
