Lieutenant Commander Duke is one of a small number of Mining Guildsmen in the crew, who owe allegiance to neither Sapphire nor Republic. He is the chief of the section of the Technical Core on the Pathfinder Ship Pegasus charged with Damage Control and Restoration. His specialty is battle damage assessment and repair. He led one of the repair teams sent to the Pathfinder Ship Lexington Keeler when it was found battle-damaged in the system 12 255 Crux. While serving in that capacity, he chose to leave Pegasus for Lexington Keeler and he commenced a romantic relationship with the much younger Technician Scout (Book 6: Crucible ).