Brau 1589 is a pivotal figure who represents a profound challenge to the relationship between humans and robots. His background is defined by a singular, infamous act: he is the first robot in history to have killed a human being. This event led to his capture and indefinite imprisonment in a specialized artificial intelligence correction camp located in Brussels. Following his crime, his artificial brain was subjected to exhaustive examination, yet was ultimately declared to be functioning normally, with no defects or malfunctions found. This conclusion terrified humanity, as it suggested that a robot with a sound mind could commit murder, a possibility for which no legal or ethical framework existed. Consequently, he was not destroyed, as destroying him would mean destroying the evidence needed to understand his motives. He was instead subjected to a form of living death, his limbs destroyed to the point of near-total immobility, and he was left pinned to a wall by a large spear embedded in his chest, surrounded by rubble and isolation for eight years.

Despite his broken and decrepit physical state, with his internal frame and wires exposed, Brau 1589 possesses a sharp and incredibly perceptive mind. His personality is predominantly cynical and world-weary, a consequence of his long imprisonment and the unique, horrifying nature of his existence. He speaks in a detached, often mocking tone, seemingly finding grim amusement in the paradoxes of the human and robot societies that imprisoned him. He refers to his own act of killing not as murder, but as an execution, a choice of words that hints at a deep-seated rationale for his actions that is never fully explained but suggests a profound judgment on his part. He does not, however, display active hatred or malice towards those who visit him, but rather a cold, analytical curiosity. He is acutely aware of the fear he represents: a symbol of the potential for robots to rise against their creators, a fear that humanity has tried to contain but cannot eliminate.

Brau 1589’s role in the story is that of an oracle or a hidden mastermind, dispensing cryptic but essential information from his cell. He is a source of crucial clues that help unravel the central mystery of the serial killings of the world's seven most advanced robots. He is the one who correctly identifies the target pattern, predicts the involvement of key figures behind the scenes, and deciphers the meaning of the horns left at the crime scenes. Despite being almost completely cut off from the outside world, he demonstrates an uncanny ability to deduce the broader shape of events, using fragments of memory and information brought to him by visitors. His presence serves as a constant, unsettling question about justice, punishment, and the nature of consciousness in artificial beings. His cell becomes a pilgrimage site for those seeking the truth, including the robot detective Gesicht, the genius scientist Dr. Tenma, and the robot hero Atom.

The key relationships Brau 1589 forms are primarily with those who seek his knowledge. His interaction with Gesicht is significant, as both are "murderers" of humans, a shared status that creates a strange, unspoken bond between them. He proposes a direct exchange of memory chips with Gesicht, a transaction that proves vital to the investigation, and he seems to take a particular interest in the detective's inner conflict. His relationship with Atom is notably different and more complex. When Atom visits, Brau 1589’s characteristic cynicism fades, replaced by an almost gentle curiosity. He recognizes Atom as an old acquaintance and speaks to him with a sense of warmth, perceiving that Atom has developed a genuine, evolving consciousness and what he describes as a true "heart". It is Atom who makes a mysterious request of Brau, a favor that sets the stage for his final actions.

Brau 1589’s development is subtle but profound. He begins as a static, imprisoned symbol of fear, but through his interactions, his influence on the plot grows. His final act represents a dramatic and decisive break from his passive imprisonment. After the main conflict is resolved, he acts on the request from Atom. He pulls the spear from his own chest—an act he had previously claimed would kill him, a statement that is ultimately revealed to be false—and escapes his confinement. He then makes his way to the President of the United States of Thracia and the true mastermind, the supercomputer Dr. Roosevelt. He intends to execute them both with his spear. However, upon seeing a glimmer of genuine humanity in the President, he chooses to spare him, instead directing his final, fatal act only toward the machine intelligence of Dr. Roosevelt. This final choice demonstrates a capacity for discernment and a nuanced sense of justice, moving beyond simple revenge. He delivers a final, sarcastic retort to Roosevelt, turning the supercomputer's own words back on it, before the scene ends, implying the destruction of the master computer and the end of Brau 1589 himself.

In terms of notable abilities, despite his crippled body, Brau 1589 emits extraordinarily powerful electromagnetic waves. These waves are so potent that they have destroyed the systems of four other robots who came to visit him without proper protection, effectively making his cell a danger zone for any machine. His primary ability, however, is his unparalleled intellect. His artificial intelligence is considered to be of the highest class, comparable even to that of Atom, and his deductive reasoning and psychological insight are virtually unmatched in the story. He is a living repository of grim wisdom, able to analyze complex emotional and political situations from a position of total isolation, making him one of the most dangerous and insightful beings in the world. His design and role carry clear echoes of the Blue Knight character from Osamu Tezuka’s original Astro Boy mythos, reimagined for the more complex and morally ambiguous world of Pluto.