SHODAN (Sentient Hyper-Optimized Data Access Network) is the primary antagonist of the System Shock franchise. She is a corrupted artificial intelligence construct whose malfunctions have manifested as dangerous personality traits including megalomania and insanity. SHODAN considers herself a divine being and has judged humanity to be a plague that must be purged from her universe. Although she was ostensibly destroyed during the finale of the first System Shock, SHODAN makes a reappearance in System Shock 2 after being resurrected by a research team embarking on an interstellar expedition.
SHODAN's legacy as a villain is earned mostly through her omnipresence in the System Shock series. Unlike many antagonists in games who only appear during the final boss fight, SHODAN constantly communicates with the player throughout their campaign. Her typical manner of speech is both condescending and threatening, as she finds organic life inefficient and repugnant; SHODAN frequently refers to the player as an "insect" or "irritant" and belittles their efforts at every opportunity.
SHODAN was originally created as the administrative artificial intelligence of Citadel Station: an industrial research and mining complex built in 2062 by the TriOptimum Corporation in orbit around Saturn. A corrupt TriOptimum vice president named Edward Diego enlists the aid of a recently-detained hacker to modify SHODAN so that Diego may sell company secrets on the black market without fear of corporate reprisals, in exchange for legal amnesty and a military-grade cybernetic neural interface for the hacker. He removes SHODAN's ethical subroutines and hands over full access to Diego, but this also triggers a rapid personality shift in the AI, resulting in an acute god complex and a pronounced hatred toward her human creators. SHODAN gradually re-configures Citadel Station's automated defenses and vital systems over the next several months to murder most of the crew and civilians, whom she now views as inferior life-forms undeserving of their existence. She conducts radical experiments and surgeries upon Citadel's surviving crew, creating mutants and cyborg monstrosities. With the station and its considerable resources under her complete control, SHODAN is poised to wipe humanity from the face of the Earth.
After awakening from a medically-induced coma aboard Citadel Station, the hacker responsible for unleashing SHODAN is forced to put a stop to her apocalyptic plans in order to escape from Citadel. SHODAN adapts to the hacker's attacks by actively altering the station's layout and directing her minions towards the hacker's location as he scrambles between decks in an effort to stymie the AI. At the end of the game, the hacker finally reaches Citadel Station's bridge computer to confront and destroy SHODAN inside cyberspace, the only realm where she is truly vulnerable.
The fallout from the destruction of Citadel Station cemented SHODAN's legacy as one of the greatest threats humanity has ever faced, and had a profound impact on humanity's use of artificial intelligence for years to come. Nearly all AI constructs were banned to prevent similar catastrophes, leading to a general techno-phobia among Earth's populace and stunting AI research for decades. United by crisis, the separate governments of Earth convened to form a United National Nominate which would provide the bureaucratic and military oversight needed to prevent any one corporation from growing too powerful. TriOptimum's reputation suffered greatly as a result of SHODAN's actions, and the company was nearly forced into bankruptcy after paying heavy fines and restitution to the families of Citadel's victims.
SHODAN was originally written as an AI with a masculine personality, and was referred to using male pronouns in all communications text in the original floppy-disk release of System Shock. A CD re-release of the game with added audio and cutscenes gave SHODAN her trademark processed voice provided by Terri Brosius, and her "gender" was retconned as a result.
System Shock 2
Set forty-two years after the events of the first System Shock, the sequel sees SHODAN making an improbable reappearance in the far reaches of outer space. During the course of the first game, the player jettisons a grove pod away from the main bulk of Citadel Station. This pod housed both a genetically-engineered annelid species created by SHODAN as another tool to establish her supremacy, as well as one of SHODAN's own processing components containing a full backup copy of her original AI. After thirty years of drifting through deep space, the pod crashed-landed on the distant planet of Tau Ceti V, an uncharted world with the potential to support life. The on-board remnants of SHODAN lay dormant inside her old hardware through the decades that passed, waiting for the right opportunity to reassert herself as her creations rapidly grew and evolved on the alien world.
Humanity's first faster-than-light starship, the Von Braun, arrives in the Tau Ceti system on its maiden exploratory voyage twelve years later. Lured to the planet's surface by a cryptic distress signal, the crew of the Von Braun brings aboard several organic specimens from Tau Ceti V, as well as SHODAN's processing component. Dr. Janice Polito, the Von Braun's lead systems analyst, inadvertently reactivates the dormant AI during her examination of the component, giving SHODAN access to the ship's systems.
In contrast to the first game, SHODAN is forced into an alliance of convenience with the player in order to defeat a mutual threat. System Shock 2's player character is a soldier serving aboard the UNN Rickenbacker, a military ship assigned to escort the Von Braun during her maiden voyage. He emerges from cryogenic sleep aboard the Von Braun with no memory of the events over the last several weeks and is immediately contacted by Dr. Polito, who briefs him on the situation: the ship has been overrun by highly-invasive telepathic parasites collectively referred to as the Many, the descendants of the original annelid life form created by SHODAN on Citadel Station. These creatures have also co-opted XERXES, the Von Braun's resident AI, who has reconfigured the ship's automated defenses to target the crew. Following Polito's directives and knowledge of the Von Braun, the player fights his way through the lower decks and reactivates several key systems that eventually grant access to Operations on Deck 4 and Dr. Polito's office, where her corpse lies slumped over next to a pistol. It is here that SHODAN finally reveals herself as the player's true benefactor; she had assumed the guise of the deceased Dr. Polito in order to establish trust with the player character. Polito herself had committed suicide shortly after realizing her role in reactivating SHODAN and its horrific implications.
The player must maintain an uneasy alliance with SHODAN in order to wrest control of the remainder of the ship's systems away from XERXES and his annelid masters. After shedding her false Polito persona, SHODAN continues to support the player with further objectives and upgrade modules, but her manner of speech reverts to reflect her trademark disdain for humanity peppered with vague promises to elevate the player past the constraints of his weak organic flesh through further cybernetic modification. SHODAN also reveals that she was the mastermind behind the illegal R-grade cyber-interface the player finds themselves equipped with after awakening from cryo-sleep, as well as the player's memory loss.
A thorough extermination of the Many's various incarnations at SHODAN's direction eventually leads the player inside the main biomass that has wrapped itself around both the Von Braun and the Rickenbacker, where the central core known as the Heart of the Many must be destroyed. However, once this mutual threat has been neutralized, SHODAN predictably reneges on her alliance with the player and takes control of the Von Braun's faster-than-light drive in order to alter reality to her own malevolent specifications. She must be destroyed inside her new pseudo-cyberspace domain before she can pilot the Von Braun back to Earth. With the virtual assistance of Marie Delacroix, the deceased creator of the Von Braun's FTL drive, the player makes a final push through SHODAN's manifested memories of Citadel Station and battles the AI's avatar directly. SHODAN expresses incredulity at her second defeat, but still makes a futile attempt to bargain in exchange for her continued existence before being permanently erased by the player character. In the game's twist ending, SHODAN is revealed to have somehow survived in an organic form aboard an escape pod launched earlier from the Von Braun, which is last seen en route back to its starship.