Deja is the AI, or Artificial Intelligence, that runs the Han for Dr. Halsey. Deja helps Dr. Halsey by running database scans. Déjà also puts up pictures, graphics and other information on the screen for Dr. Halsey's review. Dr. Halsey created Deja for the purpose of the Spartan Project.
When Deja appears, she is a hologram. She looks like a Greek Goddess. She has white hair and she wears a toga and no shoes. Number 117's first experience working with an AI is when he works with Deja.