When his friend Harold blackmailed Dr. Corso into using his weapons expertise on his gang, "Kneejerk" was outfitted with cybernetic limbs, which enhanced his reflexes to superhuman levels. Additionally, his new limbs were equipped with chainsaws capable of cutting through solid steel, which could be deployed from his wrists and knees. With these gadgets, Kneejerk could open safe doors, or create escape routes for his team. However, the chainsaw blades impaired his balance. During a fight with Batman, he fell, causing the saws on his knees to jam into the ground and break off. The piston he left behind brought Batman to Dr. Corso.
When Batman traced the gang back to their hideout, Kneejerk was the first member to be subdued once Batman had determined the self-destruct code for their cybernetic systems. When Kneejerk cornered Batman, the latter spoke the phrase "April Moon," causing the former's forearms and lower legs to self-destruct. Once his prosthetic limbs were destroyed, Kneejerk fell helplessly to the ground, unable to get up.