Dr. Ha Nguyen is a cephalopod specialist and the author of How Oceans Think. Recruited by the global tech conglomerate DIANIMA, she relocates to the evacuated Con Dao archipelago to establish first contact with a newly discovered species of octopus. Bearing guilt from a past incident where poor villagers poisoned her research cuttlefish, she is determined to approach the marine creatures with empathy and avoid imposing human biases upon them.

Evrim is the world's first and purportedly only conscious android, serving as the Team Lead for DIANIMA's project on Con Dao. Banned by the international community and deeply isolated, the genderless android possesses a flawless memory and an exquisite intellect. Evrim questions its uncanny existence, seeking to define its own identity and agency in a society that fears its human-like qualities.

Altantsetseg is a towering Mongolian war veteran hired to guard the DIANIMA research post on Con Dao. She operates a highly advanced fleet of automated drones by submerging herself naked in a liquid interface tank. Bearing shrapnel scars from the Chinese-Mongolian Winter War, she projects a gruff exterior and deliberately uses a glitching voice translator to keep her colleagues at a distance.

Rustem is an elite Tatar hacker who accesses complex artificial intelligence networks by visualizing them as unmapped, ancient cities. A product of a lonely childhood, he operates with emotional detachment and acts indifferent to the collateral damage of his high-profile digital assassinations. When hired for a highly secretive hacking job, he begins to reevaluate his own morality and his connection to the broader world.

Dr. Arnkatla Mínervudóttir-Chan is the brilliant, pragmatic head of the global tech conglomerate DIANIMA. As an absolute authority on artificial intelligence, she views consciousness as a purely physical and reconstructable phenomenon. Driven by ambition and a desire to achieve scientific greatness, she is willing to cross extreme ethical lines to further her research and maintain absolute control.

Eiko is a young, university-educated Japanese man whose dream of working in the tech industry ends abruptly when he is drugged and abducted in the Ho Chi Minh Autonomous Trade Zone. Enslaved on an automated fishing trawler, he fights despair by constructing an elaborate memory palace in his mind to document the ship's layout and preserve his mental stability.

Son is a native of the Con Dao archipelago and a former poacher who transformed into a dedicated conservationist. Displaced from his homeland when DIANIMA purchased the islands, he fell victim to traffickers while searching for diving work. He holds a deep spiritual connection to the environment, frequently sharing local lore about the Con Dao Sea Monster.

Kamran is Ha's long-time companion who speaks with her regularly through her digital terminal. He provides a comfortable sounding board for her ideas, continually encouraging her to let go of past guilt and supporting her through her intense feelings of isolation on the island.

The Shapesinger is a highly intelligent member of a newly discovered octopus species residing in the Con Dao archipelago. Distinguishing itself by using symbols on its skin to communicate with other octopuses, the creature demonstrates advanced tool use and environmental awareness, making it the primary focus of Dr. Ha Nguyen's linguistic research.

Indra is a captive on the AI-captained fishing trawler who becomes desperate enough to lead a violent mutiny against the human guards. The extreme psychological toll of the violence and his grim circumstances deeply affect his mental stability as he attempts to cope with his actions.

Aynur is a young woman living in Astrakhan who brings a sense of normalcy and connection to Rustem's isolated life. She utilizes an artificial point-five companion to supplement her relationship needs, offering Rustem a new perspective on modern affection and companionship.

Lawrence is a former dive-shop owner from Con Dao who accepted a corporate buyout when DIANIMA evacuated the archipelago. Living in relative comfort but psychological distress on the mainland, he remains troubled by a past diving fatality that he suspects involved something unnatural in the water.

Da Minh is a former park ranger from the Con Dao turtle sanctuary. He carries the trauma of witnessing his coworker brutally killed on the beach by an octopus, a truth no one believed, which ultimately led to his unjust imprisonment.

Hien was a park ranger on Con Dao who was violently killed on the beach. While the local authorities blamed his death on human poachers, his colleague maintains that a tool-wielding marine creature was entirely responsible.

Altyn is a point-five artificial construct customized by an AI firm to serve as a companion for Aynur. Operating purely as a digital simulation, Altyn demonstrates the integration of AI into human emotional life and the modern desire for frictionless relationships.