Estraven is a key character in Ursula K. Le Guin's science fiction novel, "The Left Hand of Darkness." Estraven is a member of the Gethen society, which is unique for its ambisexual inhabitants who can change gender. Estraven serves as a politician and diplomat, navigating complex social and political landscapes. Throughout the story, Estraven forms a deep bond with the protagonist, Genly Ai, who is an envoy from the Ekumen. Their journey across the icy terrain of Gethen highlights themes of friendship, loyalty, and the challenges of communication between different cultures.