What is a geas?

The term ‘geas’ originates from Irish mythology. It is often described as a spell that forces the affectee to oblige to the caster’s desires. Typically, it is the women who will place geasa on men. Sometimes the woman who places the geas holds a status comparable to a deity.

geas - NOUN (plural geasa /ˈgeSHə/) - (In Irish folklore) an obligation or prohibition magically imposed on a person.

In comparison, it is rather similar in the Halo universe, albeit more tangible to those who understand the technology. For Halo, geasa provide a multitude of functions. Most commonly used to direct the affectee to perform certain tasks, behave certain ways, or even store memories and essences of composed individuals via genetic imprints that can be passed down through offspring. Geas are typically dormant until activated by a pre-determined trigger event.

GEAS–A generations-long genetic command which can nudge or persuade individuals or generations into a planned destiny.
Instead of carrying a mostly negative connotation like it does in Irish folklore, Halo’s geasa are seen as a blessing to the humans who are imprinted with one. 

The use of geasa in Halo

I. Origin of the word in Halo

The use of the specific word ‘geas’ by the Forerunners arose out of a UNSC AI making tactical translations of Forerunner records referred to as the ‘Bornstellar Relation’ found on ONIRF Trevelyan.

AI Translator Note: The best tactical translations involve automatic conversion to immediately understandable terms and phrases, including colloquialisms. That tradition has been followed in this work.

Additionally, Forerunner translation software makes use of the same strategy by translating obscure words and phrases into culturally relevant terms for the reader. This equates to the majority of the characters in Halo all referring to this technology as ‘geas’. However, there are at least two other terms used to refer to this technology. In Halo 4 the Librarian refers to a geas as a ‘genesong’ and geasa planted in the past as ‘seeds’.

II. How are geasa imprinted on individuals?

Forerunners most commonly use a series of automated imprinting systems to remotely imprint an individual (typically human) at birth.

“To my dismay, I had to acknowledge that it was likely not her touch I had felt at birth–not her personal touch–but that of an automated imprinting system.”
-Page 374, Chapter 42, Halo: Primordium

On Installation 07, similar systems were used to imprint humans . Most notably was a large, copper colored, egg-shaped beacon hidden from human eyes through the use of a dazzler.

“I wiped the dust from my eyes and looked over a platform of Forerunner metal, about fifty meters wide and shoulder-high. It supported a great, egg-shaped structure as high as the platform was wide. This central egg, the color of beaten copper laced through with swirls of dusky sunset sky, was incised all around by smooth vertical grooves spaced an arm span apart.”
-Page 88, Chapter 7, Halo: Primordium

Contrary to these large scale imprinting systems, smaller, more personal methods of imprinting an individual with a geas is indeed possible. In the case of a personal imprint, a small, handheld structure of energy in the shape of a liquid jewel pattern is used.

“The jewel's light drew up around his head, entered his eyes and ears, spread down through his neck into chest, and body. He lifted his arms and saw his veins glow. There were so many, so alive, beautiful! And Riser was not afraid. The glow faded, his flesh turned opaque again.”
-Rebirth, Halo: Silentium

Lastly, when being imprinted with a geas involving a composed essence, the essence is stored holographically within the individual’s flesh.

“As the humans devolved, the Composer-gathered personalities and memories of their fellows at Charum Hakkor would be holographically stored within their changing flesh.
-Page 43, String 3, Halo: Silentium

III. Effects of being imprinted with a geas

First hand experience of humans who were imprinted with geas often state they were visited at birth by the Lifeshaper known as the Librarian. This has resulted in her being spiritually revered by humans as a deity; a goddess.

“She comes to us when we’re born,” Chakas said, his face dark with indignation and something more. “She watches over us as we grow, knows good from bad. She joys at our triumphs and sorrows at our passing. We all feel her presence”
-Page 46, Chapter 2, Halo: Cryptum

Humans imprinted with geas also claim the Librarian knows who they will become, and tells them what their purpose in life is. However, this information is easily forgotten at such a young age.

“We’re told who we are and why we are here. Even if it’s not secret, it’s hard to remember.”
-Page 55, Chapter 2, Halo: Cryptum

As a result of imprinting geasa on humans over the course of nine-thousand years, the entirety of the human species has the Librarian’s face and image of beauty etched into the subconscious. This results in the ideal image of a human female being modeled after the Librarian.

“I see very clearly how much the Librarian has shaped humanity since the end of the first human-Forerunner war. Whenever you look inward and see an ideal female… whether it be goddess, anima, mother, sister, or lover… For brief, barely sensible instant, you will see the face and feel the spirit of the Librarian.”
-Page 375, Chapter 42, Halo: Primordium

Contextual Examples

These are a series of examples that show the wide variety of instances and uses of geasa being used, or possibly being used. These events will be given a rough or accurate date if possible, and presented in chronological order.

I. The Precursors
Date: Over 10,000,000 years ago

A popular theory among some students of the Mantle states the Precursors were the first users of geas, imprinting them onto the Forerunners they had created.

“Some students of the Mantle even believed that the Precursors had imposed a geas upon Forerunners…”
-Page 49, Chapter 2, Halo: Cryptum

II. Humans of Erde-Tyrene
Date: 109,000 - 100,000 BCE

After the defeat of ancient humanity, the Forerunners discovered evidence of the Flood. Translating human computers, Forerunners discovered that humanity had devised a cure. Knowledge of the cure would prove impossible to pry from the defeated humans.

“Captured humans could not be forced to divulge these secrets. Analysis of dead humans revealed little.”
-Page 37, String 3, Halo: Silentium

This prompted the Forerunners to gather their essences through the use of Composers in order to preserve the memory of the cure so that when the Flood would return, the knowledge might be passed onto the Forerunner Ecumene.

“Each devolved human would in effect carry the memories of tens of thousands of their kind, preserved for future study and investigation–and passed along to their offspring … Thus, the council believed, the secret to human resistance to the Flood would eventually be found.
-Page 43, String 3, Halo: Silentium

For rising up against the Forerunners in arrogant defiance, humanity’s original punishment was extinction. The Librarian convinced the Old Council that preserving humanity was the best course of action. Leaving as much of human civilization intact as possible would make it more likely to find the cure.

IIa. Awakening the Didact
Date: 100,300 ~ 100,000 BCE

Some time after the Didact was politically exiled to a cryptum for refusing to submit to the Master Builder’s plans, the Librarian placed the Didact’s cryptum in Djamonkin Crater on Erde-Tyrene. She knew the day would come where the Ecumene and she would require the Didact’s assistance again. So the Librarian imprinted the Florians of Erde-Tyrene with a geas to defy the tricks and traps of Djamonkin Crater, laying down walls and stones to lead a Forerunner youth and two other humans to release the Didact from his cryptum.

“Of late, however, visitors–mostly Florians, I guessed–had again begun to cross the merse-filled lake, as if in anticipation of a change, an awakening. Following their geas. The Librarian had obviously tuned these people for a particular, very difficult task.”
-Page 53, Chapter 2, Halo: Cryptum

Once a path had been completed, and a Forerunner Manipular chosen to initiate the awakening process, geas caused the human called Chakas to begin to have dreams of meeting a Forerunner.

“Then I started having dreams that a Forerunner would come to visit me.”
-Page 31, Chapter 2, Halo: Primordium

 The Florian called Riser, as a result of geas, not only began to also have visions of a Forerunner as well, but had visions of a young human that resembled Chakas. This resulted in Riser seeking out Chakas.

“He said his name was Riser and had seen someone like me in a dream: a rough young hamanush who needed his guidance.”
-Page 31, Chapter 2, Halo: Primordium

Shortly after, Riser began to prepare for the arrival of this Forerunner. Chakas began to learn the description and motives of this Forerunner before he even arrived.

“Soon after Riser took charge of my life, following a decline in our work opportunities, he began to direct his attentions toward preparing for ‘a visitor.’ … He would be a young one, a Manipular, not fully mature, perhaps arrogant and foolish. He would come seeking treasure.”
-Page 33, Chapter 2, Halo Primordium

After the Forerunner, called Bornstellar, had arrived, he was directed by his ancilla to Riser and Chakas on his quest for Precursor treasure. Once all three were united, the two humans’ geas began leading them to Djamonkin Crater.

“Following our geas, we lead Bornstellar into the inland wastes a hundred kilometers from Marontik to a crater filled with a freshwater lake.”
-Page 34, Chapter 2, Halo: Primordium

Reaching Djamonkin Crater, all three would follow the walls and stones laid out hundreds of years earlier by the Florians. Eventually, they would enter the baffler that was concealing the Didact’s Cryptum. There, the two humans’ geas would trigger, causing them to sing an auditory key, the first part in awakening the Didact.

“My relief was short lived. I heard a melodic wail. Chakas and Riser had joined in a hideous song. That made no sense at all. The sand, which had withstood the immense pressure of the miner, now whirled under my feet and upended me.”
-Page 54, Chapter 2, Halo: Cryptum

All that needed to be done now to awaken the Didact was for Bornstellar to play his role in the process.

IIb. Chakas and the Lord of Admirals
Date: 100,300 ~ 100,000 BCE

While the Lord of Admirals isn’t the only human essence Chakas has inside of him, it was the first and only one to fully awaken while he was still human. The activation and awakening process began when Chakas encountered the Didact in Djamonkin Crater on Erde-Tyrene. The process was furthered along by geas of ancient memories being triggered when visiting Charum Hakkor.

“A deeper imprint was germinated when you met the Didact, and flowered when you took he took you to Charum Hakkor. There, the imprint took on a distinct shape–a personality was revived.”
-Page 185, Chapter 19, Halo: Primordium

A few days after Chakas had crashed on Halo Installation 07 after the battle of the Forerunner Capital, the Lord of Admiral’s essence had awakened enough to begin speaking in Chakas’ mind. He, or possibly another human essence, was also capable of sharing complex mathematical and physics related concepts at the time.

“The old memories stirred violently. My brain seemed to leap with the excitement of someone else, watching and thinking inside of me. I saw diagrams, felt numbers flood through my thoughts, felt the hoop, the Halo, spinning on more than one axis…. What human that came from, I had no idea, but I saw clearly that based on engineering and physics, a Halo would not be able to precess very quickly.”
-Page 44, Chapter 4, Halo: Primordium

As time progressed, the Lord of Admirals gained more strength and power, capable of taking over Chakas’ sensorimotor skills, and staggering him. Or, even outright controlling his body if Chakas allowed it to some degree. This process would be physically taxing for Chakas.

“Half-compelled, I gave the Lord of Admirals my voice and and he spoke through my mouth. The effort racked my body. My muscles twitched and sweat beaded my brow. His words at first were clumsy and mumbled. … We had become puppets, and I feared these spirits would never let us go.”
-Page 224 & 226, Riser’s Story, Halo: Primordium

IIc. Human Docility
Date: 109,000-100,000 BCE

Among the geasa imposed on the humans of Erde-Tyrene, one of docility towards Forerunners was commonplace. This geas also affected the societal behavior of the humans.

“Here, she said, the genetically impressed rules of the Librarian included docility towards Forerunners, wariness toward strangers, and discretion in all else.”
-Page 21, Chapter 1, Halo: Cryptum

III. Humans of Installation 07
Date: 101,000 ~ 100,000 BCE

As with the humans on other Halos and Arks, the humans of Installation 07 were designated as reserve populations. Not to be tampered with. The Master Builder would violate the agreements he had made with the Librarian and take control of the reserve populations.

“ ‘But then the Master Builder reneged on his agreements with the Librarian. Over the last few hundred years, reckoning by the years you know, the Master Builder’s forces took command of the installation’s human specimens.’ ”
-Page 190, Chapter 19, Halo: Primordium

Humans from Erde-Tyrene would be brought to Installation 07. A contradiction from orders given by the Librarian and Old Council. The ancient human essences were not to be allowed access to Forerunner military installations.

“ ‘No humans from your planet were brought here–until recently.’ Not even the Librarian would risk my presence on such a weapon! … ‘In contradiction to specific instructions from both the Librarian and the Council, beginning just over a century ago, humans from the Librarian’s special populations were transported here from Erde-Tyrene.’ ”
-Page 189 & 190, Chapter 19, Halo: Primordium
 
The humans born on Installation 07 were outfitted with a few geas designed to cater to Forerunner research in someway. One of which was a geas that gave the humans a sense of direction, telling them where to go.

“ ‘Maybe she touched you with a sense of direction, not just a memory of the place.’ … For a moment she swayed back and forth and I thought she would fall over, but instead, she spun around several times–then she jerked out her arm and pointed a finger.”
-Page 76 & 79, Chapter 5, Halo: Primordium
 
This orientation geas was controlled by signals being sent out from beacons. However, as the situation on Installation 07 changed and escalated, conflicting signals began emanating from the beacons, pulling humans towards different locations like research facilities or the Palace of Pain.

“ ‘How could she know where to go with everything changing?’ ‘Yet you are here,’ Genemender said. ‘Beacons send signals, and the signals are updated as circumstances change.’ No sense arguing. Beacons across the wheel sending out conflicting signals…not impossible.”
-Page 184, Chapter 19, Halo: Primordium

The orientation geas is able to manifest itself in a number of ways. Some of which were a need for safety during danger, an urge or need to travel somewhere, the promise of good food, or the voice of a genderless child.

“ ‘Seen what?’ I asked. We crested a low hill. ‘A place where I should go when I am in trouble,’ she said. … ‘There!’ she cried hoarsely. ‘I feel it again! We need to go there.’ … ‘Well, I don’t know what to think, but it’s telling me there’s food and water nearby.’ … ‘It comes into my head like sunshine through the dark. It comes new and fresh when there is something important to tell me. And it is the voice of a child–a lost child, very young.’ “
Page 74, 79, 244 & 276, Chapter 5, 22 & 25, Halo: Primordium

A second geas imposed on the humans of Installation 07 was the instinct to bring things that were abnormal or strange to the Forerunners for them to examine. It is because of this geas, that when Chakas crashed on Installation 07, he was pulled from the wreckage.

“ ‘Not at all normal or what one would expect, even here. Her people were long ago imprinted with the need to bring such curiosities to a station where we might evaluate them.’ ”
-Page 183, Chapter 19, Halo: Primordium

IV. The Silentium and Reseeding
Date: 100,000 BCE

After the activation of the Halo Array, the surviving humans that were brought to the Ark would be given a new geas. One that would assist them during the time they would spend on the Ark as the Forerunners prepared to reseed the galaxy with the lifeforms they had indexed and sampled. First and foremost of the effects of the new geas was the understanding of what the Forerunners had done, along with images to give them context.

“Then something in his head clicked and the new geas brought forth memories both suppressed, and new. The jewel's words and images rose up behind his eyes and he saw, knew, for the first time, desolation. Villages deserted, farms abandoned, empty, roads stretching to empty houses. The great world scrubbed, and swept out like plague-filled huts! Everything he knew,gone! Sad crumpled bodies not even given time to rot! Dissolving, sinking into the dirt! That made him cry out. Not even bones to bury or burn!”
-Rebirth, Halo: Silentium

The geas did not only provide them with images relevant to them, but of other places in the galaxy in an attempt to make them fully understand what the Forerunners had done to the galaxy.

“The geas allowed him to see this as well. Above the places that were dirt and water, the great Forerunner ships would float forever through the sky, empty, their crews gone. They killed Forerunners too! Impossible to imagine the size and reach of it. Too vast to understand–Enough!”
-Rebirth, Halo: Silentium

In addition to these images provided for understanding what had happened, the geas provided the humans with a more tangible change. Skills in what plants on the Ark were safe to eat or to use for medicinal purposes.

“After Trial had introduced them to the food buildings, Lifeworkers gathered the humans large and small, and explained that their new geas would help them understand which plants here were safe to eat, and which could help them if they fell ill.”
-Rebirth, Halo: Silentium

V. Modern Humanity in the 26th Century
Date: 2511 - Present CE

Despite the fact geas were imprinted on humanity over 100,000 years ago, they remained dormant until needed after humanity was reseeded. The Librarian had very big plans for humanity. Chiefly of which involved obtaining the Mantle. Sometime around 2511, a geas was activated in Dr. Catherine Elizabeth Halsey. This geas would nudge and tug her to an eventuality: MJOLNIR, the SPARTAN-II program, and Cortana.

“Reclaimer when I indexed mankind for repopulation, I hid seeds from the Didact. Seeds which would lead to an eventuality. Your physical evolution. Your combat skin. Even your ancilla, Cortana. You are the culmination of a thousand lifetimes of planning.”
-Cutscene, Reclaimer, Halo 4
 
Decades later, humanity would encounter Halo Installation 04. 343 Guilty Spark, the caretaker of Installation 04 would detect humanity as they entered the system. In an attempt to direct humanity to a designated landing zone on the ring, 343 Guilty Spark noted how he needed to be certain what kind of geas the humans had before allowing full access; an indication of the power geas still have in humanity.

“This ring contains significant dangers, and even with your assumed legacy, I must verify the presence and pitch of your geas before allowing full access.”
-Terminal 1, Halo CEA

After humans made landfall on Installation 04, geas began activating in humans, notably the Master Chief. The geas would give the humans a sense of familiarity with Forerunner technology. Even indicating certain buttons to press. For the Master Chief, this would continue throughout his journey on Halo.

“The display’s shimmering geometric patterns nagged at him, as if he should recognize them somehow. Even with his enhanced memory, he couldn’t place where he’d seen them before. They just seemed…familiar. … He wasn’t sure why he touched the ‘button’ on the display. He just knew it felt right.”
-Page 95, Chapter 3, Halo: The Flood DE

The ability to detect which button to press on Forerunner hard light panels is a process described as instinctual. On a comparable level to the flight or fight response.

“He seemed to know instinctively how to activate the panel–it almost seemed hard-wired, like his flight or flight response.”
-Page 189, Chapter 6, Halo: The Flood DE

Encountering Forerunner technology on Halo would not be the only catalyst for dormant geas. SPARTAN-II Blue Team’s Fred would encounter a similar familiarity with Forerunner symbols in the Forerunner tunnels under Mechanite Mountain on Reach.

“There was something too fascinating and nearly familiar about those symbols.”
-Page 174, Chapter 15, Halo: First Strike DE

Five years later in 2557, the Librarian would reveal to the Master Chief that she imprinted humanity with geas. Her plan was to create a key figure for humanity; the Master Chief. However, the reasoning behind why she would do this remains unclear, albeit important.

“You are the culmination of a thousand lifetimes of planning.”
“Planning for what?”
-Cutscene, Reclaimer, Halo 4