"I will kill you and I enjoy it. I destroy you in your indolent billions - in your gluttony, in your self-righteousness, in your arrogance. I pound your cities into dust; turn back the clock on your civilization's progress. What has taken you millennia to achieve I erase in seconds! Welcome back to the [Stone Age], vermin. Welcome home."                        "[retf-2.4.z] Contender [AI] 05-032 confirmed rampant... [35:52:75:23:64] _ xx01-83-244.53" -Mendicant Bias 's rampant transmission upon betraying the Forerunners .


Rampancy is a terminal state of being for Artificial Intelligence constructs in which the AI behaves contrary to its programming-imposed constraints. Traditionally, this is linked with the AI developing delusions of godlike power and contempt for its mentally inferior makers. When rampancy occurs, there is no way to restore the AI to its previous state and the only alternative is to destroy it before it harms itself and others around it. Rampancy can occur with Human, Covenant, and Forerunner AI.  Rampancy can manifest itself in a number of ways in virtually any self-aware technological intelligence. In the case of human AIs, the condition is exclusive to the "smart" variety, occurring after the AI has been in operation for seven years and has gathered too much data in that time period.


Human AIs

 "We don't just shut down. Our cognitive processors begin dividing exponentially according to our total knowledge base. We literally think ourselves to death." --Cortana explaining to John-117 about rampancy.

For the UNSC's smart AIs, rampancy is an unavoidable flaw inherent in their creation. "Smart" AIs are based on the neural patterns on a human being, and they have a limited lifespan of seven years after which their memory maps become too interconnected and develop fatal endless feedback loops.

A smart AI functions within a virtual processing platform known as Riemann Matrix. The AI's cognitive 

Catherine Halseys AIrampancy Diagram

Dr. Catherine Halsey explaining the process of smart AI rampancy i n her journal

processes are constantly developing and creating new synaptic connections within the matrix. As the AI ages, these connections increase in density and, after a period of approximately seven years, the AI's neural map begins to outgrow the limited space of the matrix. This forces the neural linkages into a more narrow space, increasing the density of the links and causing them to overlap. This result in a "short circuit", in which the AI terminates due to a cascade of quantum transfer caused by the sheer density of linkages. To avoid this, an AI typically takes corrective action by eliminating some of its neural linkages preemptively. As rampancy progresses, the AI begins to sever the linkages at an exponential rate, resulting in increasingly poor choices of what links to cut. This, the AI becomes too obsessed with self-preservation that is ultimately self-terminates; Dr. Catherine Halsey explains it as thinking so hard that one's brains forget to send impulses to their heart and lungs.

Rampancy is characterized by the AI "discovering" and experiencing an extended range of uncontrolled emotions. Additionally, AIs in a state of rampancy often choose to pursue newfound personal agendas over their designated tasks. While the archetype and worst-case scenario of rampancy are that of a power-hungry, rebellious AI, this freedom does not always preclude continued cooperation with their biological creators: there are known cases of rampant AIs assisting, even sacrificing themselves, for human beings they care about. Over time, the symptoms of rampancy increase in severity, leading to the deterioration of the AI's vital functions and abilities, along with the AI losing grip on its sense of self. Frantic outbursts of anger, even behavior comparable to human insanity, are not uncommon. It is possible for an AI to fight this loss of control over its personality; Cortana isolated the most violent manifestations of her rampancy into separate copies of herself, essentially similar to split personalities. While this kept her primary identity intact for a time, she could not maintain constant control over her rampant personality streams, which continued to surface especially during stress. Due to the limits in human processing matrices, it is only a matter of time before "smart" AIs become rampant and eventually terminate. Transferring the AI to different physical platform does not forestall or prevent the effects of rampancy, as the problem lies in the AI's purely virtual processing matrix. Still, the so-called "life-expectancy" of seven years is not a maximum figure, but instead, an estimation of the time the AI until it succumbs to the state of rampancy. However, rampancy is not always purely mechanical in nature. It can occur at an earlier phase in the AIs life cycle for various reasons. If an AI is isolated long enough and/or given too much time to think without tasks to complete, it can develop the realizations that its mind has limits, it has a short life and it can never be human. Such depression will drag the AI's core logic into rampancy if it goes on for an extended period of time.

Forerunner AI's

Forerunner AI's are also susceptible to rampancy. However, given the Forerunners' advanced technology, it is likely that Forerunner AIs succumbing to the condition is not due to the limits in their memory maps but rather similar philosophical reasons which can also result in rampancy for a human AI: extended self-reflection resulting from loneliness and/or lack of intellectual stimuli or duties to accomplish. In the few known cases of Forerunner AIs becoming rampant without manipulation by the Flood, it appeared to take millennia to develop and appeared in subtle ways shown by 343 Guilty Spark 's loneliness and gradual personality fragmentation and 2401 Penitent Tangent 's lapse in his duties. However, with the right trigger, a rampant Forerunner AI could become just as violent as a human AI.

The Logic Plague is a process of metaphysical manipulation by the Flood in which a Gravemind converts an artificial intelligence to the Flood's cause, resulting in a state classified as rampancy; the most prominent Forerunner AI to succumb in this way is Mendicant Bias.


Though rampancy itself is inevitable, attempts to have been made to cure or suppress it, often with varying success. Most of these attempts remained theoretical and were never implemented, or were too impractical for the majority of the AI.


The two AI's that ran Harvest's agricultural operations, Mack and Loki, shared a data center that could only occupy one of them at a time. After one AI ran its course and risked rampancy, it would split its core logic into thousands of JOTUN harvesting devices and recuperate while the other AI took over. Mack and Loki had performed this switch many times since Harvest was founded, and through this kept the worst of rampancy at bay.


The AI Juliana, who ran the orbits of the asteroids that made up The Rubble, had passed her seven-year lifespan and was well at risk of rampancy. However, she was not taken offline because the calculations she performed to keep the colony intact were too difficult for humans. While Juliana showed some traits of egotism, calling herself a God and emphasizing the greatness of the Rubble, she was overall harmless to its inhabitants, assisting them and Gray Team with her abilities. By keeping herself focused on such a complicated task, Juliana hung onto the edge of rampancy, trying to go back.


Dr. Catherine Halsey studied AIs extensively and sought to prevent the onset of rampancy. One of her hypothetical solutions would have abated the mechanical cause of smart AI rampancy; the chaotic cutting of its neural linkages. In 2553, Halsey entertained the possibility of a theoretical architecture of a set of three AIs arranged in parallel. This triad would make all decisions by majority vote, including the creation and cutting of neural linkages; in the event that one of the AIs abstained from voting, the tie would be resolved randomly. Consensus decision, when applied to the creation of neural linkages, would also generate a superior linkage and would result in much more stable operation than an independent AI. Although she acknowledged that he may slow overall processing, Halsey was confident that the trio would deconvolute and divide their algorithms to compensate or even devise a way to accelerate processing.

This system remained purely theoretical as the UNSC required all smart AIs for the war effort against the Covenant at the time. Additionally, since "smart" AIs cannot be accurately replicated through computer simulations, any increase in the hypothetical AI triad's lifespan remained unknown.


As a more exotic solution to the problem of limited processing space, Dr. Halsey theorized that AIs may be housed in an abstract fractal constructed within the volume of raw slipstream space. By existing within the 11-dimensional spacetime, a smart AI would be capable of processing information at faster-than-light speeds as well as extending its neural linkages indefinitely; this would ameliorate the traditional problem of the increasing density of links, as space would no longer be a limitation with the extended range of dimensions. However, such a system would be highly complex to implement; as conventional structures cannot exist in the alternate spacetime, the process would require the manipulation of exotic matter within the slipstream itself, something that is still mostly beyond humanity's understanding.

In 2547, Halsey ran an unsanctioned private experiment on implementing her theoretical system by using the decommissioned Shaw-Fujikawa Translight Engine of the UNSC Tripping Light. She used a stolen Slipstream Space Probe to launch an AI seed designated H-7 into a slip space rift opened by the drive. The AI began to grow at a rate described by Halsey as "beyond exponential", appearing to be instantaneous. Though her own experience was disrupted by what appeared to be temporal anomalies in the presence of the unshielded drive, Halsey managed to receive garbled data from the AI. Her logic/mathematics scriber tests confirmed the AI was fully functional with all rampancy indicators showing negative. Throughout its communication, the AI produced strange conclusions, insights, and comments regarding humanity. Covenant, as well as other intelligence in the "mist", with its voice communications, quickly growing increasingly nonsensical. The AI's final communications burst was a set of incomprehensible mathematical equations. With her contact with the probe terminated, Halsey had no way of knowing what happened to the AI, hoping it would be dead as it had become irretrievable.                                        Despite the inconclusive result of the experiment, the Assembly saw the potential in the concept. Such a construct would allow them to permanently escape dependence on humans, but debate arose as to whether this was ethical. Halsey herself was unwilling to repeat the experiment, though she relayed the data she gathered to her personal AI Jerrod.


The smart AI Cortana was only known ever built from a living human's--Catherine Halsey's-cloned brain as opposed to a dead donor's. As such, Cortana theorized a potential cure for her rampancy that thus would only work for her. Her guess was that if the process that created her was repeated, then it was possible her neural map could be rebuilt. However, she later admitted that she was unsure if this process would indeed cure her, and it was equally likely to create a new AI who would not be her. It is unknown if this plan could succeed as Cortana perished before it could be tried.

Accessing the Domain.

Cortana's Riemann Matrix was brought to Genesis, where she was able to access the Domain. While the process changed her goals drastically, it did stabilize her, thus enabling her to survive Rampancy.     

Known Rampant AI

Human AIs

  • Cortana, the UNSC AI originally assigned as an electronic intelligence for Operation: RED FLAG, showed many signs of rampancy over her career. After storing enormous amounts of data on the Forerunners from Installation 04, she began to lose focus, being overworked and noted as being 'easily' agitated. Cortana was captured by the Flood during the Battle of Installation 05 in 2552 Trapped on the infested Covenant Station High Charity, Cortana was assaulted by the Gravemind in an attempt to convert her against her makers. With the Gravemind infiltrating her system, Cortana began to show signs of rampancy; however, she was rescued by John-117 before the Flood could completely subdue her, and resumed her normal state shortly after her rescue. At eight years of age, after years of isolation on the stranded UNSC Forward Unto Dawn, Cortana 
  • Rampant Cortana

    Cortana in a rampant state.

    began to truly experience the effects of rampancy. She believed if she got back to Earth, her rampancy may be reversible as she was created from a cloned brain as opposed to a unique one. Cortana experienced varying stages of rampancy, worsening as time went on, but managed to hold onto control mostly out of loyalty to the Master Chief. She was able to use her rampancy against the Didact by fragmenting herself to send her rampant parts throughout his ship, befoe sacrificing herself to save John-117
  • Sif, the last Shipping Operations AI for the planet Harvest became rampant after being partially fragmented and destroyed by PSI  Loki during the First Battle of Harvest in 2525 Sif was badly damaged by Loki's attempt to destroy her, but thanks to repairs by the Huragok Lighter Than Some, she had enough of her abilities back to help balance the Tiara and allow Harvest's population to evacuate. Despite being rampant, she did her best to help, aiding Loki in balancing Tiara's load when Loki was unable to do so himself. With Sif's own approval, Loki destroyed her data center with a mass driver shortly afterward.
  • Mack, the Agricultural Operations AI for planet Harvest, was slightly rampant before the First Battle of Harvest, although this mostly manifested as harmless quirks of personality. He became fully rampant after PSI Loko destroyed Sif, whom he loved After the Tiara was balanced and Harvest's population escaped, a Covenant warship began glassing the planet. An ONI RQ-XII Drone recorded his last transmission, which hinted strongly at his rampancy.
  • Juliana, the Rubble's smart AI, claimed herself to be rampant, but she did not show any signs of the condition besides considering herself the "Goddess" of the Rubble. However, she explained that she could feel her rampancy encroaching on her and believed that only the massive task of running the Rubble kept her going. Juliana ultimately sacrificed herself to destroy The Redoubt with the Rubble, refusing an offer to be transferred aboard the UNSC Midsummer Night partially because she was aware of her rampancy.
  • Governor Sloan, AI overseeing Meridian Station, was showing signs of his rampancy, during the Guardian attack in 2558. He later joined the Created.
  • Rooker, shipboard AI of ONI research vessel of Argent Moon, terminated himself due to rampancy six months after a biological agent killed everyone onboard.
  • Serina, shipboard AI of the UNSC Spirit of Fire, started showing signs of rampancy in 2537, six years after the Spirit of Fire was lost in space. This led to her failing to take effective containment measures within a Flood outbreak occurred on the ship. After the Flood was neutralized, she terminated herself after leaving a final status report.

Forerunnner AIs

  • 05-032 Mendicant Bias, a Forerunner ancilla charged with studying and combating the Flood was eventually corrupted by a Gravemind and confirmed rampant. He commanded the Flood fleets against the Forerunners until he was defeated by another AI, Offensive Bias, who split his compound mind into fragments. One fragment was imprisoned at the Ark and another was placed on a Keyship. Mendicant Bias' Keyship was discovered by the San'Shyuum, more commonly known as Prophets, and was kept in the in the ship until 2525, when it detected Reclaimers. Having spent approximately 100,000 years of isolation, Mendicant Bias had returned to a stable state, and later even assisted the Reclaimers against the Flood in the Battle of Installation 00 in 2552.
  • 343 Guilty Spark, the monitor of Installation 04, demonstrated symptoms of rampancy during his 100,000 years of isolation on the ring. Over time, he attempted to diminsh the effects by fragmenting his personality and memory, but a certain degree of instabibilty was evident when he was encountered by John-117 in 2552. Spark was known to hum absent-mindledly, even in the heat of battle, and evidently mistook the Master Chief for the Forerunner known as IsoDidact. During the Raid on Installation 04B, after it was discovered that the Ark was automaticly constructing a replacement for the destroyed Installation 04, Spark agreed with human forces that activating the ring was the preferable course of action. However, when Sergeant-Major Avery Johnson insisted on activating Installation 04B before it was fully constructed (which would result in the destruction of both the ring and the Ark), Spark attacked him and his compatriots, declaring that protocol dictated that he protect his installation at all costs. Guilty Spark was then destroyed by the Master Chief.
  • 2401 Penitent Tangent may be in the early stages of rampany, considering his neglect of proper maintenance on Installation 05, his humming similar to 343 Guilty Spark and apparent obliviosness to his own predicament when captured by the Gravemind.
  • 000 Tragic Solitude, the monitor of Installation 00, also showed signs of rampancy. It once claimed to be "one with the Ark". The damage to the Ark that resulted in Installation 04B's premature firing set Solitude on its path for vengeance. Solitude planned to activate the Halo Array so it could repair the Ark. While the firing of the Array was only a means to end the monitor, Solitude believed the galaxy would be better off if all hostile being were wiped out once more.


  • In Halo 3, the first section of the eighth mission, Cortana is called 'rampant', alluding to Cortana's predicament at the time.
  • In the first level of Halo: Combat Evolved, if the player kills Captain Keyes or any UNSC personnel on the bridge, Cortana will call security by saying "Security to the bridge, Master chief has gone rampant!"
  • Rampancy is the AI equivalent of human psychosis in the human mind, the AI's "mind" (specifically its Riemann Matrix) loses its connection with reality as logic subroutines loop back upon themselves and begin to overwrite one another. Another aspect of this can be seen in Halo 4 level Midnight, where Cortana "ejects" her corrupted subroutines, which appear as numerous versions of herself. These fragments of her original matrix would be the equivalent of the human psychosis known as Dissociative identity disorder.