In his debut episode Nano, Harry "The Schlub" Parker was a petty con artist and street vendor. After ripping off a man's wallet, Harry ran into the Nanobots which, using Harry's broken toy robots, created a body. Harry was petrified at first, but became intrigued by the criminal possibilities of Nano, which he quickly figured out could be used to bypass security systems. He used the nanite swarm to break into several stores around and in the 2nd Time Around store, and eventually robbed that store as well. However, on his way out, he was caught red handed by Casey Jones, only to have Nano intervene on his behalf and easily beat Casey.
However, the Turtles were also on the premises, and came down to confront the would-be thief. Harry was horrified by the presence of "Martians" and begged Nano to protect him, which the childlike bot did. He later speculated that the Turtles were from the same place that Nano came from, and that they might be trying to take him back.
Harry was present when the Turtles attacked Nano in the junkyard, initially by using their weapons and then by crushing its robotic body. However, Nano was ultimately immobilized by a large electromagnet, which Harry tried to free his "son" from. However, the electromagnet was suspended over a furnace, and when it lost power due to Harry's intervention, Nano fell into a mass of molten metal. Harry was immediately stricken with guilt and grief over the loss of the innocent Nano, begging forgiveness even as the police arrived to arrest him.
He spent some months in prison before the events of The Return of Nano, when he was transferred to a new prison. He had just been caught cheating in a card game when Nano broke into the prison and brought his "daddy" to freedom. However, Nano had absorbed the idea of a happy nuclear family, and thus wanted to create one with Harry and his creator Dr. Marion Richards. Nano also attempted to make Harry happy by giving him the stolen loot from their previous crime spree, but was enraged when Harry asked to be let go. Harry was trapped inside Nano when the nanobot swarm threw a massive tantrum, which ended only when it was hit with a massive electromagnetic pulse.
Harry was arrested again and sent back to prison despite his protestations that he had been kidnapped.