EDI

EDI (pronounced 'Eee-Dee' [ˈiː.diː]), which stands for Enhanced Defense Intelligence, is the AI of the Normandy SR-2 and is represented by a holographic floating blue sphere at various terminals throughout the ship where she can provide basic information about the Normandy and Cerberus. EDI is voiced by Tricia Helfer.

EDI is a Quantum Blue Box type AI and functions as the electronic warfare defense for the Normandy and because of the potential danger of a rogue AI, she has been given behavioral blocks and can't interface with the ship's systems. She also serves as the Illusive Man's eyes and ears on the Normandy, monitoring the many listening devices on board and sending regular reports to him.

The Illusive Man restricted Shepard's access to some of EDI's files and capabilities for unknown reasons, although EDI surmises that the reason is probably because he does not want Shepard to know everything about Cerberus just yet. It is only later in the game, after acquisition of the Reaper IFF and its integration with the SR-2's systems, in which a virus disables the ship, enabling the Collectors to board and capture nearly the entire crew while Shepard and the squad are away, Joker grants EDI access to the ship's full array of systems, enabling them to escape. EDI can then reveal that the Normandy SR-2 was built using technical diagrams of the SSV Normandy SR-1, which was built by the Alliance upon the encouragement of Cerberus. The SR-2 was assembled using parts bought from various vendors, and built by Cerberus in a remote area of the Voyager Cluster.

EDI also gains access to "Anti-Reaper Algorithms" later in the game, and states that she devotes significant processing power to analyzing them. When pressed on this subject by Shepard as to how she could hope to combat beings millions of years more advanced, she reveals that she was in part designed by technology gained from Sovereign's remains and thus, at least partially, based on Reaper technology herself.

At the end of the game, Shepard has the choice to betray the Illusive Man and leave Cerberus. If this is the case, the issue of the numerous tracking and monitoring devices Cerberus has on the Normandy is not elaborated on, although it appears Shepard has earned EDI's loyalty and as an AI, she would be free to stop sending reports to the Illusive Man.

Personality
Being an AI, EDI's behavior goes beyond typical VI interactions, with the ability to act independently and develop relationships like any sentient being.

Her most important relationship is with Joker. As the Normandy's pilot, he is directly responsible for her well-being. At first, Joker is apprehensive of EDI, believing that starships can operate well enough without an AI's assistance. However, as the game progresses their relationship improves, though they pick on each other. After the attack by the Collector ship on the Normandy, EDI states that she and Joker have developed an "equitable working relationship". After the final mission, EDI states that they have developed a kind of platonic relationship, which she surmises is not related to any kind of hormonal attraction on Joker's part. This is reflected in how they address each other- at first EDI calls Joker "Mr. Moreau", but later starts calling him Jeff, and Joker at times responds to EDI as "mom", reflecting his viewpoint of the relationship.

EDI appears to have an understanding of humor, as she has made numerous comments of intentionally humorous nature, especially after being unshackled during the Reaper intrusion aboard the Normandy. She appends such comments, or humorous comments made by others, with the phrase "That was a joke." This sense of humor could also be described as poor, as her jokes are often disconcerting rather than funny.