Captain Hobbes is the commanding officer of the HMS Leviathan, the massive living airship that serves as the central setting of the story. His background is rooted in the Darwinist military hierarchy, where he holds the rank of captain and oversees the crew of the bioengineered vessel. As a leader, he is portrayed as pragmatic and duty-bound, prioritizing the success of his missions and the safety of his ship. He does not discover the true gender of Deryn Sharp, who serves under him disguised as a boy named Dylan, and he judges her solely on her performance, considering her a capable and reliable soldier. This assessment leads him to personally award her a medal and later assign her a dangerous but critical task during the engagement with the German warship Goeben. His motivations are aligned with the Darwinist cause and the broader war effort, though he also demonstrates a willingness to cooperate with former enemies when circumstances demand it, such as when he negotiates a temporary truce with Prince Aleksandar and his companions. In terms of development, Captain Hobbes remains a steady, authoritative figure throughout the series, offering guidance and orders without undergoing major personal changes. His key relationships include his professional bond with the crew, especially with Deryn Sharp, whom he trusts as a competent airman, and with other officers such as Dr. Nora Barlow, whose scientific work he respects. His notable abilities lie in naval command and strategic decision-making, particularly in high-stakes aerial battles and the coordination of the Leviathan's unique biological systems.