The Pitcher was Fagin's chief drug tester and his best hitman. He possessed an abnormally strong metabolism. Any drug that made him sick would kill someone else, which was why Fagin found him to be a useful guinea pig (if it made the Pitcher sick, Fagin would not sell it). The Pitcher became so tolerant to drugs that only Fagin's newest drugs gave him any "satisfaction".
The Pitcher got his nickname from drinking a full pitcher of grain alcohol "to no effect" and killed the woman who gave him the nickname. The Pitcher's mind had been so damaged by drugs he could not even recall his own name (and always called Fagin "the Bald Man" because he could not remember that, either). He walked by stomping, which was easier since "the accident".
The Pitcher hated everyone except "the Bald Man" and his grandmother. The former granted him drugs so new that they had not been made illegal yet, while the latter was the only person who knew his real name, leading the Pitcher to believe that killing her might not have been a smart move.
The Pitcher was such an efficient hitman that no one had escaped his grasp for years.
The Pitcher's catch phrase was "brutal!" used in the way a 21st century person might say "cool!". He was covered in piercings and holo-tattoos of a large person (e.g. himself) committing acts of violence on a small person (e.g. his victims).
Over the years, the Pitcher murdered numerous people he had not been assigned to kill, such as his grandmother, and a woman at the Firefly Club who asked about his tattoos.
Fagin did not have a full understanding of Nova's psychic abilities when he dispatched the Pitcher to kill her. The simple task of walking from the mouth of the alley she was living in to reach her was hampered by the Pitcher's constant drug use, augmented by multiple dispensers of different drug types - he literally forgot his mission halfway through, and went through fantasy sequences of how she would die. He was surprised that she could scream without a throat, until he realized he had not killed her yet; he was getting careless. When she read his mind and said what she saw in it, he assumed he had been speaking out loud. His plan was to literally rip off her arms and then kill her by beating her with her own arms. Nova realized he was insane (because he had suffocated a woman at the Firefly Club who asked about his tattoos) and promptly killed him using her mental powers.