Daniel O'Connell co-owns the Keaton & O'Connell Assurance Investigating Office with Taichi Hiraga-Keaton, operating from their Baker Street headquarters in London. Their partnership originated nearly a decade before the main events when Daniel, investigating the demise of one of Keaton's former employers, recruited Keaton after recognizing his exceptional observational and combat abilities. This collaboration formally began in 1982.

Daniel anchors the agency's London operations, focusing on administrative duties and client coordination while Keaton handles global fieldwork. This division aligns with Daniel's preference for office-based tasks over external assignments. He adopts a pragmatic approach to workload management, frequently delegating intricate or demanding cases to Keaton. Their dynamic includes lighthearted banter, with Keaton occasionally employing dry humor to remark on Daniel's delegation tendencies.

Daniel possesses blonde hair, though his age, family history, and personal life remain unelaborated. Functionally, he sustains the agency's operational framework to enable Keaton's investigative missions. Throughout the series, Daniel persists as a consistent professional fixture in Keaton's career.