Ancilla

Ancilla was a Forerunner term for an artificial intelligence construct. They came in several varieties, each designed for different purposes and possessing differing capabilities.

Background
Ancillas could be housed within personal shells like those of the Monitors, as well as ships, buildings, and various forms of machinery. The most powerful ancillas, next to the Contender-class, were the Metarch-class ancillas. Not all ancillas assumed visible form, such as those that operated within a metarchy; a vast network of ancillas coordinated by a Metarch. Ancillas possessed varying personalities, often approximating that of a Forerunner. The Forerunners used software known as AI suppressors to disable ancillas.

Ancillas were also stored within a Forerunner's body armor and could be accessed by the user at will for information and guidance. Most personal ancillas assumed the form of a blue female Forerunner; however, an ancilla's appearance would be modeled according to the species of the individual wearing the armor. For a Manipular, a personal ancilla made itself easily "visible" and readily accessible to the young Forerunner. But once the Forerunner mutated to first-form, the ancilla made itself less visible so it can divert power to other tasks, making it more difficult for the user to access them. It is also apparent that ancillas helped Forerunners access the Domain after mutation.

Varieties

 * Monitor
 * Metarch
 * Contender-class artificial intelligence

Trivia

 * Bornstellar's relationship with the Librarian's ancilla is similar to that of John-117 and Cortana. Like Cortana, Bornstellar describes his ancilla as a "blue female figure in the back of his mind" who can be stored within his body armor, and relies upon her for guidance and help in many situations.
 * "Ancilla" is Latin for 'female slave', 'female servant' or 'maid'.

List of appearances

 * Halo: Combat Evolved
 * Halo 2
 * Halo: Ghosts of Onyx
 * Halo 3
 * Halo: Contact Harvest
 * Halo Wars
 * Halo: Helljumper
 * Halo: Blood Line
 * Halo Legends
 * Origins
 * Halo: The Flood (2010)
 * Halo: Cryptum