Monitor

Monitors are advanced artificial intelligence constructs, or ancillas, created by the Forerunners to occupy special positions in their society. Monitors are characterized as being embodied in floating robotic casings, in contrast to most ancillas which lack physical form, only appearing as holographic representations. Most prominently, monitors were tasked with servicing and maintaining the Halo installations and ensuring that the virulent Flood stay imprisoned. Beyond their most well-known function, monitors were assigned to a wide variety of tasks by the different Forerunner rates, ranging from robotic household servants to security, combat support and duties involved with the Conservation Measure. Monitors also oversee the maintenance and function of many Forerunner facilities, including the Line installations. Monitors are extremely intelligent, yet are completely devoted to their original function; for example, monitors whose duties involve combating the Flood are zealous about containing the parasite, and 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' photoreceptors vary in color, including blue, red, orange and green. However, some, if not all monitors' photoreceptors can change color; for example, 343 Guilty Spark's photoreceptor was generally blue, though it turned red when he was in a combative state. 2401 Penitent Tangent's and 686 Ebullient Prism's photoreceptors were perpetually red, despite no evidence of combat-related behavior. The Warden's photoreceptor was dull green.

343 Guilty Spark and 2401 Penitent Tangent both possessed high-pitched, tinny voices. 049 Abject Testament's voice also had a tinny quality, but was notably deeper.

Function and behavior
Each Halo installation has a single custodian monitor assigned to it, which oversees all operations on the ring. Line Installation 1-4 was overseen and maintained by a single monitor, 686 Ebullient Prism. Numerous monitors were used to provide security for the Forerunners' Capital Court. Monitors were sometimes used in combat by Warrior-Servants, and hundreds were used aboard Lifeworker ships involved with the Conservation Measure. Monitors also served individual households. The Warden was a venerable monitor serving on the Capital that was used to both detain accused criminals and to defend them in court.

Most known 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's monitor commands the Sentinels of the installation they oversee. The latter two are only activated if a catastrophic Flood outbreak occurs. The only known monitor of a Line installation, 686 Ebullient Prism, also 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 installations' monitors, an overeagerness to activate the Halo Array should the need arise. 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's monitor sees its 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. This is due to the compartmentalization protocols enacted by the Forerunners, which intentionally limit a monitor's knowledge by design so that as little as possible would be divulged should it be captured by the Flood; this measure became particularly essential after the widespread perpetuation of the parasite's logic plague. This data compartmentalization was most prominently demonstrated with 343 Guilty Spark, large portions of whose memories were erased or suppressed after his assignment to Installation 04. During the Battle of Installation 04, and later on Installation 04B, 343 Guilty Spark seemingly addressed SPARTAN John-117 as the IsoDidact.

Features
Monitors have a remarkable resistance to small arms fire, though they will eventually succumb after taking extensive damage. On Installation 04B, 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 an Aggressor 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 directed energy beam that is 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 unlock doors in Forerunner installations and can repair some technology.

Monitors have access to their assigned installation's translocation grid, allowing them to quickly move across the span of the installation. For long-distance travel outside their installations, monitors are equipped with impulse drives.

Monitors' software intrusion capabilities are significantly beyond those of the defenses of the modern-day UNSC; even in a barely functioning, all but destroyed state, 343 Guilty Spark bypassed ONI's AI-enhanced computer security aboard with startling ease. Over the course of these intrusions, Spark was also able to covertly upload his personality construct array into the ship's computers and take control of the ship; this did not become apparent to the ship's AI or the crew until moments before the monitor announced its plan to them.

Known monitors and their assignments

 * 03-049 Abject Testament - Installation 03
 * 04-343 Guilty Spark - Installation 04, later Installation 04B
 * 05-2401 Penitent Tangent - Installation 05
 * 686 Ebullient Prism - Line Installation 1-4
 * The Warden - Detained and provided defense for Forerunners accused of crime before the Capital Court.

Trivia

 * In Halo: Combat Evolved and Halo 3, monitors' eyes are branded with the Marathon symbol. The symbol has been altered in Halo: Reach and Halo: Combat Evolved Anniversary for copyright reasons.
 * 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 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 to edit the map. However, unlike fought Monitors like 343 Guilty Spark, they have the same shield strength as normal players and no attacking options other than ramming or dropping large objects on hostiles.
 * In Halo: Reach Forge, a monitor will bleed if shot with its shields down.

List of appearances

 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo 2
 * Halo 3
 * Halo Legends
 * Origins
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * The Return
 * Halo: Blood Line
 * Halo: Reach
 * Halo: Cryptum
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: Primordium
 * Halo 4
 * Halo: Silentium