The unnamed protagonist is an intellectual who prides himself on his ability to observe and categorize human behavior. Recovering from an unspecified sickness, he spends his time sitting alone and studying the faces of passing Londoners. His intense curiosity drives him to stalk a stranger through the city streets for an entire day and night. He views himself as superior to the general public while choosing to remain solitary and hidden from their view.

An older, frail figure who roams the streets of London continuously for days at a time without resting. He wears filthy but beautifully textured clothing and carries a concealed dagger and diamond beneath his cloak. He walks comfortably through busy commercial districts but becomes highly agitated and panicked whenever the masses thin out. He constantly seeks the cover of densely populated spaces to avoid being alone.