Déjà

Déjà was a "dumb" AI who trained the Spartans in their first stages of training at the CASTLE Base and Reach Naval Academy facilities on Reach. Her educational lessons were part of the Spartan's training program, meant to increase their strategic thinking. She also educated them in history, mathematics, and other things most people are taught. In one of her first lessons, she taught the Spartan-IIs about the famous Battle of Thermopylae, where 300 Spartans made a stand against a quarter of a million Persians. Another lesson was about 7|seven wolves taking down a moose, by working as a team.

Her counterpart, Chief Petty Officer Franklin Mendez, gave the Spartans rigorous physical training to make them into soldiers. This, along with Dr. Catherine Halsey's physical augmentations and MJOLNIR armor, made the Spartans intelligent, strong, and fast.

Déjà also acted as a sounding board for Dr. Halsey, discussing how the Spartan-II Program should be run. For example, the night the program officially began she advised Halsey on how to address the children. Later they would discuss whether Halsey was giving Soren-066 the choice to proceed in the program in order to alleviate her own conscience.

Her current fate is unknown. As a "dumb" AI, her lifespan is, in theory, indefinite. Déjà was seen on Reach in 2552, residing inside CASTLE Base. She may have been destroyed when the Covenant glassed Reach, although the area around CASTLE was undamaged. However, she is never seen in Halo: First Strike, and Dr. Halsey never mentions her again.

Déjà took on the form of an ancient goddess wearing Greek robes.