Brown assists the main detective protagonist throughout the narrative. He works alongside the detective and partners with Audrey, an investigator from the international police force Wanterpol, to confront the antagonist Shiriarty. Their alliance forms during the investigation into Shiriarty's attempts to steal the treasure known as "O-PARTS." Brown participates in efforts to prevent Shiriarty from obtaining the O-PARTS and achieving his goal of plunging the world into darkness. His role centers on supporting the detective's investigative work during this central conflict.