Mickey Miller is a CIA officer renowned for his top-level intelligence skills. He sports spiky blonde hair, green eyes, and a medium build. His polished exterior masks a sharp tongue and incongruous behavior that unsettles those around him, revealing eccentric tendencies beneath his professional demeanor. Miller is fluent in Japanese, English, French, and Mandarin Chinese.

Within the narrative, Miller acts as an antagonist, competing directly against the protagonists to secure the Tesla Fragments – pieces of Nikola Tesla's technology capable of distorting space and time. He operates within the CIA alongside colleagues Oliver Thornton and Lily Steiner. Miller's motivations are focused on securing these powerful artifacts for U.S. interests, placing him in direct opposition to the main characters during international conflicts over the fragments. This mission is complicated when Thornton is revealed as a mole working for the antagonistic organization Small House. Miller's narrative role centers on advancing the core conflict over the Tesla Fragments through his professional actions and rivalrous interactions.