Monitor

Monitors are highly advanced artificial intelligence constructs, or Ancillas, created by the Forerunners over 100,000 years ago to occupy special positions in Forerunner society. One of their main purposes is to service and maintain the Halo installations and to ensure that the virulent Flood stay imprisoned. Other purposes include the maintenance of Line installations. Monitors are extremely intelligent, yet are completely devoted to their original function, and are zealous about containing Flood; Monitors have been known to turn violently on their allies if they should attempt to violate their containment protocols. The Covenant refer to Monitors as Oracles; they revere the "Oracles" for their wisdom and believe that they are key to the fulfillment of the Great Journey.

Appearance
A Monitor's body consists of a roughly spherical shape that is concave on three sides, with an illuminated photoreceptor located on the front of the orb. A Monitor's silvery metal covering is reminiscent of other Forerunner constructs, though their spherical shapes stand in contrast to the polygonal, angular shapes commonly seen in other Forerunner creations.

Monitors' photoreceptoprs have a variable hue. For example, 343 Guilty Spark's photoreceptor was generally blue, though it turned red when he was in a combative state. However, 2401 Penitent Tangent's and 686 Ebullient Prism's photoreceptors were perpetually red, despite no evidence of combat-related behavior, though the former case may have been due to proximity to a Gravemind. Some Monitors feature green photoreceptors. Whether eye colors vary between Monitors, between their action or emotional states, or both is unknown.

343 Guilty Spark and 2401 Penitent Tangent both possessed high-pitched, tinny voices, though it is unknown whether this is characteristic of all Monitors.

Function and behavior
Each Halo installation has at least one Monitor assigned to it, with Installation 05 having at least two: 2401 Penitent Tangent and a large Monitor fitted to a monorail, which oversaw a Flood research facility. Line Installation 1-4 had only one known Monitor, 686 Ebullient Prism.

Monitors are identified by a series of numbers followed by a name. The Monitors of the Halo installations have identification numbers comprised of seven raised to the power of the Monitor's installation's number minus one (7n-1). The names appear to consist of an adjective describing a negative emotion followed by a technological term. In Forerunner communication logs, Halo Monitors are identified by their installation's number, a dash, and their own number; for example, 343 Guilty Spark, the Monitor of Installation 04, is identified on such logs as "04-343."

Each Halo Monitor commands the Sentinels, Sentinel Majors, Enforcers, and Constructors of the installation they monitor. The latter two are only activated if a catastrophic Flood outbreak occurs. The only known Monitor of a Line installation, 686 Ebullient Prism, commanded its installation's Gatherers.

Monitors are extremely intelligent, but are also devoted to their original functions and to protocol; this results in a zealous attitude toward containment of the Flood and, in the case of Halo installation Monitors, an overeagerness to activate the Halo Array. Monitors frequently cite protocols as explanations for their actions, no matter how impractical; this has been known to confuse or annoy human and Covenant forces who have interacted with them. It is possible that a Halo Monitor sees their protocols as the only options in a situation; during the Battle of Installation 04, 343 Guilty Spark could have taken numerous precautions to prevent the Flood from spreading across the installation, but the only action he ever considered was the activation of the Halo. During the Battle of Line Installation 1-4, 686 Ebullient Prism frequently informed his human and Covenant prisoners that they would be killed and dissected in an effort to find immunity to the Flood, showing no concern for the subjects' well-being. The Monitors' adherence to protocol is also shown in their seemingly standardized method of introducing themselves: "Greetings. I am [Number] [Name]. I am the Monitor of Installation [Number]."

Similarly to a human "dumb" AI, Monitors seem to have nearly limitless information of their own expertise, yet apparently lack information that does not pertain to their defined purpose. During the Battle of Installation 04, and later on Installation 04B, 343 Guilty Spark seemingly addressed SPARTAN John-117 as the Didact.

Monitors keep daily logs of all things that occur on and within their installations. As with human artificial intelligences, Monitors can be subjected to Rampancy, a form of multiple-stage "insanity" that affects human "Smart" AIs. This is likely due to their isolation for over 100,000 years. 05-032 Mendicant Bias, a Contender-class AI tasked with defeating the Gravemind during the Forerunner-Flood War, was corrupted by the Gravemind and delberately entered a Rampant state. Over 100,000 years later, the AI began to regret its actions, seeking to attone for its deeds by aiding the UNSC and Covenant Separatist forces during the Battle of Installation 00.

Features
Monitors have a remarkable resistance to small arms fire, though they will eventually succumb after taking extensive damage. On Installation 04B, the John-117 was able to destroy 343 Guilty Spark only with multiple discharges from a Spartan Laser, - a weapon that can destroy tanks with a single discharge - demonstrating that Monitors can sustain damage from high-powered weaponry. During the Battle of Line Installation 1-4, Reff 'Talamee severely damaged 686 Ebullient Prism's photoreceptor and casing with a Sentinel's weapon; the Monitor was eventually destroyed by its installation's main weapon. Should a Monitor be damaged, it is capable of self-repair.

Though Monitors are assisted by other constructs in the event of a Flood outbreak, the Monitors also have their own offensive capabilities. Their primary armament is a red-colored pulse beam that capable of depleting the shields of a Mark VI MJOLNIR armor suit in a single blast, as well as mortally wounding a less well-armored human. This weapon can also kill a Flood combat form almost instantaneously.

Monitors also possess two types of utility beams. One of these beams allows a Monitor to manipulate and levitate objects. The second is a blue beam that can unlocks doors on Forerunner structures.

Monitors have the ability to teleport themselves and others around their installations, likely through manipulation of slipstream space. It seems that a Monitor on an installation other than its own has no access to that installation's teleportation grid. It is possible that these limits are programmatic rather than physical; after hacking into the Core of Installation 04, the UNSC AI Cortana gained the ability to access the teleportation grids of all installations, though her inability to access the power grids restricted her usage of the grid.

Known Monitors and their assignments

 * 343 Guilty Spark - Installation 04, later Installation 04B
 * 2401 Penitent Tangent - Installation 05
 * Unidentified Monitor - Flood research facility on Installation 05
 * 686 Ebullient Prism - Line Installation 1-4
 * The Knowing - Data collection and collation on Ariel
 * 05-032 Mendicant Bias - Combat the Gravemind during the Forerunner-Flood War
 * Offensive Bias - Defeat the Rampant 05-032 Mendicant Bias

Trivia

 * In Halo: Combat Evolved and Halo 3, Monitors' eyes are branded with the Marathon symbol.
 * During the cinematic commentary on the Halo 3 Essentials DVD, Martin O'Donnell, Jason Jones, and Joseph Staten jokingly referred to the Monitor of Installation 01 as "7 Broken iPod" and the Monitor of Installation 07 49 as "49 Fucking Lightbulb".
 * A Monitor Avatar prop is unlockable on Xbox LIVE upon downloading Halo Waypoint..
 * In Forge, one can turn into a Monitor by pressing up on the D-Pad.

List of appearances

 * Halo: Combat Evolved
 * Halo 2
 * Halo 3
 * Halo: Reach
 * Halo: The Flood
 * Halo: Contact Harvest
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * The Return
 * Halo: Helljumper
 * Halo: Blood Line
 * Halo Legends
 * Origins