Fred Porlock is a significant supporting character in the anime and manga series Moriarty the Patriot, serving as one of the most trusted affiliates of William James Moriarty. He is a young man with a slim yet slightly muscular build, jet black hair, pale skin, and grey eyes. A distinctive and constant part of his appearance is the bandages wrapped around both of his forearms. His typical attire consists of a long-sleeved white dress shirt with blue rectangle cufflinks, navy blue pants held up by Y-back suspenders, a black coat, and a light blue scarf that can also be used as a hood. He is often seen carrying a pen and a small notebook in his breast pocket, which he uses to record observations and gather information.

In terms of personality, Fred is best described as quiet, reserved, and somewhat unsociable. Fellow member Sebastian Moran calls him this when they first meet, as Fred rarely speaks unless he is directly addressed or is reporting on a mission. Despite this withdrawn exterior, he possesses a deeply gentle and kind heart. This compassion is most evident when crimes involving innocent victims, particularly children, are concerned. During the incident at the Baskervilles' hunting grounds, Fred expresses a strong and urgent desire to save the kidnapped children, showing that his commitment to justice is not just theoretical but deeply personal. Sebastian Moran notes that in this respect, Fred is the most similar to William, as both of them are fundamentally unable to leave someone in need alone.

Fred's motivations are intrinsically tied to the group's overarching goal of dismantling a corrupt class system that allows the nobility to commit heinous acts with impunity. He is not a blind follower, however. His primary motivation is a refusal to accept the world's injustices as they are, and he acts on a personal conviction to protect the innocent. This moral strength leads him to occasionally question the group's plans, particularly when they might involve what he considers unnecessary collateral damage. His most significant act of defiance comes during the final arc, when he refuses to accept William's plan to sacrifice himself for their cause. Believing that William's life is too valuable to be lost, Fred acts independently and writes a secret letter to Sherlock Holmes, begging him to save William, even if it means betraying the group's immediate objectives.

His role within the Moriarty organization is multifaceted, acting as the group's primary spy, information broker, and infiltrator. He is the one who establishes a network in the East End to listen for grievances from the common people and bring potential clients, or targets, to William's attention. He is adept at tailing targets, spying on them in secret, and infiltrating their ranks often by assuming the guise of a servant to get close to them.

Key relationships define his place within the story. His most important bond is with William James Moriarty, for whom he feels deep loyalty and shares a moral vision. However, this is not blind loyalty, as his decision to contact Sherlock demonstrates a profound care for William as a person, not just as a leader. He shares a close, brotherly relationship with Sebastian Moran. He looks up to Moran as an older brother figure, and they frequently work together on missions. Moran, in turn, values Fred's skills and presence in the group. His relationship with Louis Moriarty is one of respect and cooperation, though it is tested when Louis confronts him for his betrayal in contacting Sherlock. His relationship with Sherlock Holmes is initially one of opposition, but it evolves into a desperate alliance when Fred decides that Holmes is the only one capable of saving William from himself.

Fred exhibits significant development over the course of the series. He begins as a character who is almost entirely defined by his quiet competence and his role as a tool for William's plans. However, he grows into a more proactive agent with his own moral compass. He is willing to speak up against the Moriarty brothers' decisions twice: first when he insists on saving every child at Baskerville Hall, and second and most dramatically, when he openly defies William's wishes to save his life, accepting that he may be cast out or punished for his disobedience. This act of rebellion is the culmination of his development, transforming him from a shadowy operative into a courageous individual who acts on his own convictions.

Despite his quiet demeanor, Fred possesses a wide array of notable abilities. He is a highly skilled combatant, acting as the martial artist of the group. He is proficient in hand-to-hand combat, using kicks, punches, and grappling techniques, and he is also adept with various weapons, including knives, guns, and hunting rifles. His fighting style is quick and agile, allowing him to perform feats of parkour such as jumping between carriages, scaling walls, and roof-hopping across London. Beyond direct combat, Fred is an expert in disguise, capable of creating convincing appearances to impersonate specific individuals, from a murdered woman to an old lady. He is also the group's expert in espionage, tailing, and cryptanalysis, able to both gather information and send messages in code. Outside of his criminal activities, he is shown to be a skilled gardener, cultivating a beautiful greenhouse at the Moriarty estate, a quiet hobby that contrasts with his dangerous duties.