During an experiment to tap into an extra-dimensional energy source, Niels ventured into the lab, along with a curious Robbie Baldwin, and was bombarded with the energy when the test went out of control. The result was a kinetically powered cat just like Springdale's hero, Speedball, the Masked Marvel. Niels spent all of his time evading capture by Robbie, who wanted to take him back to the lab so he could get a better understanding of his new powers. Luckily, Niels adapted to his powers faster than Robbie and got away every time. Yet, Niels luck was bound to run out some time, and it happened when the villain Rebound hired a bunch of thugs to put an end to the bouncing feline’s ways. Wanting Niels' powers for himself, Rebound hooked up the cat to a machine designed to transfer the power from cat to human. An added bonus was the capture of Speedball too, and Rebound was determined to take both of their powers for himself. Unfortunately for Rebound, Niels spit up a kinetically charged hairball which damaged Rebound's machine and ultimately led to his defeat and incarceration.
Some time after, Niels was taken to New York to live with his owner, and Baldwin, now the mentally unstable Penance, claimed Niels had become the armored and spike wearing P-Cat, the Penitent Puss. Whether this is true or not remains unconfirmed. However, Niels, taking the name Hairball for himself, answered the call of Lockjaw in forming the Pet Avengers.