- Ezio: "You are... gods."
- Minerva: "No. Not gods. We simply came... before."
- ―Ezio Auditore da Firenze and Minerva, on the nature of the Isu, 1499.[src]
As part of their unique genetic makeup, the Isu possessed a triple-helix DNA structure and had six primary senses, as opposed to double-helix DNA sequence and five primary senses of their human creations. Another trait that distinguished the Isu from humans is that they were highly intelligent; which accounts for them living for extended long periods of time. Because of this, the Isu were responsible for creating humans to use merely as a domestic workforce. Furthermore, it is believed the Isu accomplished this task by genetically modifying several members of the Homo genus using the Pieces of Eden to make humans appear anatomically similar to the their creators, with the only differences being the height and the size of the skull. As a result, early humans were unable to comprehend the Isu for what they truly were, and they mistakenly revered and worshipped them as deities.
Following the aftermath of a rebellion that was led by the Human-Isu hybrid Eve, a war broke out between the Isu and their human slaves. This war that would stretch on for ten years was coupled with the onset of what would be referred to as the "Toba catastrophe", where this event would see the Isu gradually decline and ultimately become extinct. Despite this, the legacy of the Isu lived on for thousands of years in various myths and legends, becoming the basis of many human religious ideals from Abrahamic to Polytheistic religions. Some of the Pieces of Eden managed to survive the initial catastrophe, and they became a pivotal desire for both the Templar Order and the Assassin Brotherhood, who both waged a war of their own for the Pieces.
In modern times, the Abstergo Industries' Álvaro Gramática, in his capacity as Director of Research of the Future Technology, intended to slowly clone the Isu back into existence using the Pieces of Eden collected by the company over time.
Due to their long and storied history, and the legacy that their existence left, the Isu, as a whole, were known by various names to humanity. Classified Homo sapiens divinus by Abstergo Industries, they were also intrechangeably referred to as Those Who Came Before, the First Civilization, or the Precursors,. Beyond this, certain groups of Isu, such as the Capitoline Triad, were believed by most human religions to be a part of a pantheon of gods.
Creation of humanity
- "We built you in our own image. We built you to survive."
- ―Minerva, 1499.[src]
Although the Isu were native to Earth as a product of thousands of years of evolution, their exact origins were unclear. Minerva simply stated that her kind "came before", and were responsible for the creation of Homo sapiens, forming the species in their own image to be a capable and docile workforce.  Accompanying this, the Isu created Homo neanderthalensis—Neanderthals—whom they designed to be an expeditionary or military force.
Although Minerva said that the Isu built humanity with the capability to survive harsh environments, it was Juno who made it known that humans were not intended to be "wise", thereby ensuring they were to be obedient and resilient cattle to suit their creator’s needs.
With extensive research done by Clay Kaczmarek, he seemed to suggest that the Isu had radically altered the genetic makeup of a pre-existing species of primates on the planet to create humanity, fashioning them to be similar to themselves. As a result, this altercation left a large gap with transitional species between archaic hominids and modern humans. In 1997, the Templars had become aware that this information could be damaging to how humans came into existence, so they had arranged for fake skeletons to be planted in an expedition site in Ethiopia, merely to hold accountability for this evolutionary gap and limit human exposure to the possibility of the existence of the Isu.
In order to assure their control of humanity, various technologies had been created by the Isu; the artifacts that mankind would later name "Pieces of Eden". It is believed that there were certain types of these Pieces that were able to tap simultaneously into a network of neurotransmitters located deep within the human brain, ensuring total obedience through means of remote mind control. However, there were some humans who had been born without these neurotransmitters, which was only further hypothesized by Clay Kaczmarek to be hybrids of the Isu and humans, consequently making them immune to the Pieces' mind control capabilities.
War and catastrophe
- "When we were still flesh and our home still whole, your kind betrayed us. We who made you. We, who gave you life!"
- ―Minerva, 1499.[src]
Having been instigated by the theft of an Apple of Eden by Adam and Eve, the human rebellion soon erupted into a full-scale war with the Isu. While the Isu were more technologically advanced and powerful, it was humanity had the advantage of numbers. The conflict lasted for a decade before abruptly ending when a coronal mass ejection, later to be known as the Toba catastrophe, occurred. The casualties on both sides were far greater than the Isu would have ever anticipated. The distraction of war had blinded them to all else, and their preoccupation with the conflict prevented them from seeing the signs of an impending danger from the "heavens" until it was too late.
Several Isu scientists not devoted to the war were aware of the imminent catastrophe and endeavored to prevent it by thinking up various ways to protect the Earth. The Capitoline Triad – consisting of Minerva, Juno, and Jupiter – decided to lock themselves away in the Grand Temple for years, only to test out a variety potential solutions, following which they experimented with the most promising results in underground Temples spread across the globe. Despite this, all offered prospects failed miserably, with none providing adequate protection against the massive solar flare that was due to collide with the planet.
During this time, it turns out that Juno had made her own agenda for the world. Rather than save it, she planned to rule over the remnants after the catastrophe instead. As a result, she was subsequently imprisoned by Minerva and Jupiter. With their time having grown short, Minerva managed to construct a pedestal, simply called the Eye, which allowed one to alter the patterns and equations of existence and protect the Earth by placing hidden messages for future humans throughout time, in the hope that they would find these messages, and save the world from the catastrophe's reoccurence.
However, before she could use the device, Minerva had discovered that Juno had tampered with the Eye in a manner wherein she would be freed from her imprisonment upon it being activated. Having refused to release Juno from her prison, Minerva made the decision to destroy the device instead, thus condemning the world to face a second solar flare, which would flip the Earth's weakening magnetic field and reverse the polarity where it would make the planet become geologically unstable.
In the affairs of humans
- "For centuries Tinia and I walked the world, hoping to rekindle the spark of civilization. We shared what we knew as best we could."
- ―Minerva on rebuilding civilization, 2012.[src]
While both races survived the catastrophe, few of either species remained. Working together, they rebuilt their world, though humanity continued to view their counterparts as gods. Despite their survival, the Isu were unable to fully recover their numbers, and began an inevitable decline toward extinction.
They knew, however, that the catastrophe which had burned their world before would eventually repeat itself, and so they took steps to prevent it. Utilizing a second Eye she had built, Minerva recorded a number of holographic, yet interactive, messages to serve as a warning to those who entered the Vault under what would become the city of Rome. In it, Minerva warned of the impending doom, and spoke of the "temples" that could save Earth from destruction, built by those who "knew to turn away from war". Concurrently, several other members of the Isu took independent steps to influence the thriving human race, attempting to put their knowledge to stone or parchment, though these did not withstand the test of time.. Barely a hundred years after the creation of the Temples, the Isu were almost completely extinct.
- "You may not comprehend us. But you will comprehend our warning. [...] And as life returned to the world... We endeavored to ensure this tragedy would not be repeated."
- ―Minerva to Desmond Miles, through the memories of Ezio Auditore, 1499.[src]
Delivering their message to the Assassin Desmond Miles, who was viewing the memories of his ancestor Ezio Auditore da Firenze, Minerva warned him that time was short, and that "the Cross" would stand in their way. With the deliverance of that message, one of the last remaining vestiges of the Isu faded away. Convinced they would need Ezio's Apple of Eden to locate the temples Minerva had spoken of, Desmond continued to relive his ancestor's memories, eventually tracking the artifact down to a vault beneath Santa Maria Aracoeli in Rome.
While Lucy and the others sought an alternative way in, Desmond used a series of tunnels to gain entrance into the church. Encountering projections of Juno along the way, he managed to trigger a platform that brought him and his team to the pedestal upon which Ezio's Apple rested. However, the moment Desmond laid his hands on the Piece of Eden, Juno took control of his body and forced him to stab Lucy, who was secretly a Templar sleeper agent.
Subsequently plunging into a coma, Desmond was put back into the Animus, a device influenced by, if not directly derived from Isu technology, in the hopes he would recuperate. While he and the Apple were being transported to the United States, Desmond, in his unconscious state, continued to relive Ezio's memories and was told to reach the Synch Nexus. Eventually succeeding, Desmond was pulled into the Nexus, where he encountered Jupiter, who showed him the location of the central vault, as well as a glimpse of what had happened during the Toba catastrophe.
In October 2012, Desmond and his Assassin team reached the Grand Temple, where they discovered that in order to find the key that unlocked its inner barrier, Desmond would be required to relive the memories of his ancestor, Haytham Kenway, and his son Ratonhnhaké:ton. After some time in the temple, Shaun Hastings learned that the power sources for the Isu construct were running low and that the team needed to locate more. This prompted Desmond to venture out from the Temple to recover them, and on doing so, Juno showed him visions of the solutions the Isu had attempted as he replaced them.
After he fully relived the relevant memories of Ratonhnhaké:ton, Desmond, Shaun, Rebecca and William Miles went forth to unlock the temple's large gate, where they found the Eye, which had been repaired by Juno while trapped within the temple's walls. Juno herself then appeared to the group and told Desmond that by touching it, he would save humanity. She was interrupted by the appearance of Minerva, who had used the second Eye shortly before she died, allowing her a look into the future.
Minerva's projection warned Desmond that on touching it, the pedestal would not only protect the Earth from the solar flares, but also unleash Juno into the world. She then urged Desmond to allow the flares to decimate Earth, which would lead to Desmond becoming a messiah of sorts to the event's survivors. Eventually, his wisdom would be twisted by zealots, using it to justify taking lives, thus repeating the process of humanity over and over again.
Despite this, on justifying that the choice of doing nothing was much worse than releasing Juno, Desmond refused Minerva's plea. He resolved that it was best to save the Earth and hope that another might defeat Juno, as opposed to letting countless lives be lost. Desmond then touched the pedestal and sacrificed himself, unleashing an aurora-like shield around the Earth that blocked the worst of the solar flares. After this, Juno then congratulated Desmond on playing his part, and declared that "it is time to play [hers]".
Post Second Catastrophe
Following Desmond's death, Juno uploaded her consciousness from the Grand Temple to the equipment that was brought by Abstergo Industries to inspect the scene and preserve Desmond's body, led by team leader Case Fisher. She then transferred herself to the Abstergo mainframe, while Abstergo worked on using Desmond's genetic material to create a new initiative dubbed the Sample 17 Project, run by Abstergo Entertainment, to further explore his lineage.
During her natural lifetime, despite one plan to preserve their race resulting in failure, Juno enacted a fail-safe procedure, which allowed her husband Aita to continuously reincarnate in human form. This was enabled through the insertion of 'junk code' in the human genome, which would take over a fetus during development, allowing Aita's return to life. Multiple reincarnations of Aita, colloquially referred to as Sages, were able to exist at the same time, as was the case with Thomas Kavanagh, Jr. and Bartholomew Roberts.
As of 2013, Aita had been reborn in the form of a Sage named John Standish, who worked as an IT technician at Abstergo Entertainment. Once a new research analyst came to work for the company to view the memories of Desmond's ancestor, Edward Kenway, a pirate during the eighteenth century, John sought to use their help in hacking the Abstergo information systems in return for advanced security clearance, while having the analyst pass on Abstergo's files and information to the Assassins Rebecca Crane and Shaun Hastings. It was also through Edward's memories that the analyst would learn of the Sage, Bartholomew Roberts, and his connection to an Isu complex known as the Observatory.
Despite this façade however, he was secretly manipulating the analyst into giving Juno a body to inhabit. When the opportunity finally presented itself though, Juno stated that she was unable to take over the analyst due to the fact that she was scattered too thinly and that there were more artifacts to find and more samples to gather.
Enraged by his failure, John poisoned the analyst with a low dosage in a vain attempt to allow Juno to inhabit their body successfully, though he was interrupted and killed by Abstergo security personnel, with the analyst eventually recovering from the attack.
Following John's death, Abstergo began examining his remains and discovered his identity as a Sage. Within his genes, they found a high quantity of Isu triple-helix DNA, and began the Phoenix Project in the hope of sequencing the entire Isu genome in order to use the Animus technology and find out the race's scientific secrets, with an emphasis placed on the Pieces of Eden, throughout Isu history.
After recovering a Shroud of Eden from London, Abstergo planned to use the artifact to reconstruct an Isu's body in an attempt to resurrect a member of the race – unaware to the knowledge that they were being guided towards this endeavor by Juno via her follower, Violet da Costa, in the effort to gain Juno a new body of her own.
- "The rest is up to you, Desmond."
- ―Minerva to Desmond Miles, through the memories of Ezio Auditore da Firenze, 1499.[src]
The Isu were a highly advanced and powerful race, possessing precognitive abilities, either natural or technological. This was proven during Minerva's conversation with Ezio Auditore, within the Vatican Vault hidden underneath the Sistine Chapel. Minerva revealed that Ezio was simply a conduit that allowed her to speak to Desmond Miles, who was viewing his ancestor's memories. Furthermore, Altaïr Ibn-La'Ahad mentioned in his Codex that the Piece of Eden he possessed not only contained a catalogue of past events, but also future events, implying that the Pieces held predictions made by the Isu.
It is also apparent that they had connections with many of Earth's religions, and likely influenced their developments directly. During her warning to Desmond, Minerva made mention of her former names, as well as those of her fellow 'gods'; Merva, Uni and Tinia, who later became known as Minerva, Juno and Jupiter, respectively. Their former names corresponded to the Etruscan Triad of Deities, while the latter were the names of their Roman counterparts, who made up the Capitoline Triad. This shift in names may be indicative of why various religions have numerous similarities, as they all seem to be based on the story of the Isu.
As a species, the Isu were anatomically similar to their human creations. Though unlike humanity, who were created with only five senses, the Isu possessed six, the sixth being referred to simply as 'knowledge'.
Although it is believed Isu individuals were also taller than humans, it is unclear if their skeletal structure proves this. Some Isu appeared to have had extra limbs, such as Durga, a precursor that appeared through the Koh-i-Noor who possessed an extra pair of arms; whether these were natural limbs, surgical or genetic modifications or simply part of the manifestation is unknown. Along with this, while the Isu had a longer lifespan, they were not immortal.
Following the catastrophe that set the Isu on the path to extinction, a concerted effort was made to pass on, or awaken, this sixth sense to humanity, their "final, faltering hope". Ultimately, however, they failed; though humanity could "see the blue shimmer [and] "hear the words", they did not fully possess the 'knowledge' of their creators. This consequently convinced some Isu, like Juno, that humanity should have simply been left as they were.
- "They're gifts, Mr. Miles. From those who came before."
- ―Dr. Warren Vidic on the Pieces of Eden, 2012.[src]
Despite the mark they left behind on Earth, the Isu faded into obscurity rather rapidly after their decline. However, the inability of humans to comprehend their creators as anything but gods did allow for their names and characteristics to at least live on.
Alas, the lack of evidence for their existence did not prevent select groups of humans throughout time from uncovering their true nature. By the 12th century, the Knights Templar had a limited understanding of the nature of the precursor species. Indeed, the 20th century technology used to view the genetic memories of one's ancestor – the Animus – was based on technology utilized by the Isu to record genetic memories.
The Templars also knew of the existence of the Pieces of Eden, and aimed to gather and utilize their effects to benefit their ideology, with Warren Vidic once jokingly referring to them as "gifts left behind". However, Minerva dispelled this theory to the Assassin team in the Grand Temple, by stating to them that the Templars and Assassins had wasted their time leading up to the second occurrence of the solar flare by "squabbling over [the Isu's] refuse". This situation was in significant contrast to that in the 15th century, where it had been the Assassins who knew explicitly of the existence of the precursors, whilst Pope Alexander VI, Grand Master of the Italian Templars, erroneously believed the Vatican Vault to be the location of God himself. This changed, however, and five hundred years later the Order of Assassins knew next to nothing of the Isu's existence.
Though various religious beliefs seem to have been based on aspects and misinterpretations of the Isu, their existence was largely unknown to humanity. As early as the 12th century, the Knights Templar assumed that the focus of human religions, the gods, did not truly exist, and that miracles and other supernatural occurrences were simply manifestations of the powers of the Pieces of Eden, devices created by the Isu to control the human race. However, it is unclear if the Assassins and Templars understood the origin of the artifacts at that time.
The first known instance of a human becoming aware of the Isu's existence following their extinction was that of Altaïr Ibn-La'Ahad, who made mention of them in his Codex. However, it would not be until the year 1499 that humanity would encounter the Isu again, when the Assassin Ezio Auditore da Firenze encountered a hologram of a being calling herself Minerva in the Vault located underneath the Vatican. Even though Ezio told his fellow Assassins of Minerva, they still did not understand her true nature, and Ezio himself showed great difficulty in understanding Minerva's explanation of her existence. By 2012, the Templars in Abstergo Industries possessed a greater understanding of the true nature of the Isu under their assumed aliases, and the Assassins at this time had suspicions about them as well, which were confirmed when Desmond relived Ezio's memories.
Through Desmond's experiences, the Assassins were aware of three separate beings: Minerva, Juno and Jupiter. They had previously been aware of a fourth being, Consus, as well, but it is unsure if they retained this knowledge up prior to the second solar flare. In the Grand Temple, they were also told of Juno's husband, Aita, whom she was forced to euthanize after an experiment for which he had volunteered went wrong.
- "Why do we have these gifts, these abilities? Because it's in our blood! [...] The seeds were planted as two worlds became one. Behold the Assassins, the children of two worlds!"
- ―Clay Kaczmarek, 2012.[src]
William Miles stated that one person in ten million would have a high concentration of Isu DNA. Clay Kaczmarek at one point theorized that the true reason behind the abilities of some Assassins was genetic, suggesting a lineage including both human and Isu blood. Clay's own genetic memories indicated him to be a direct descendant of both Adam and Eve, suggesting that his bloodline, if not many more, would all have access to these abilities. According to Abstergo, the average part of Isu DNA in regular humans is comprised between 0.0002% and 0.0005%, but in some individuals it can be higher, like for Desmond Miles – who had a count of 0.952% – or Sages, who had a count of Isu DNA between 5% and 6%.
Indeed, Altaïr, Ezio, Edward Kenway, his son Haytham, and his grandson Ratonhnhaké:ton, Clay Kaczmarek and Desmond Miles all possessed Eagle Vision, while Ezio and Altaïr both showed themselves resistant to the effects of the Apple, as well as Leonardo da Vinci, suggesting he too had some amount of Isu DNA. Giovanni Borgia was also another Assassin who possessed Eagle Vision, hinting that his father, Perotto Calderon, may have also had some genetic relevance to the Isu. Aveline de Grandpré, Adéwalé, Shao Jun, Arno Dorian, Arbaaz Mir, Jacob and Evie Frye, Jack the Ripper and Gavin Banks were other Assassins from different bloodlines entirely that also possessed Eagle Vision.
In addition, Ezio was able to use a Staff and an Apple of Eden, combined, to open the Vatican Vault, while Rodrigo Borgia could not, and Altaïr had previously used his Apple to enlighten the people of Cyprus to Armand Bouchart's lies. Because of this, when Desmond touched the Apple, Juno informed him that his DNA had "commune[d]" with her, activating the artifact as a result. This allowed her to control his body on a physical level, though he resisted any form of mental control, remaining completely aware of the situation he was placed in.
Unidentified Isu members
- Though they played a greater part in the plot of Assassin's Creed II, the Isu were first mentioned briefly by Warren Vidic in Assassin's Creed. When talking to Desmond, Vidic claimed that the Templars were responsible for all major human technological advances in history, though he denied that they invented them, calling them "gifts... from those who came before".
- The story of the Isu, who created humanity as a docile workforce and subsequently viewed as gods by their creation, bears striking similarity to the Ancient Astronaut Theory, which is the idea that extraterrestrials visited the Earth in ancient times and genetically altered an existing hominid species to create humanity in their own image. As a result, extraterrestrials were responsible for influencing early human civilizations, cultures, and religions; and perceived as gods by their human creations.
- The only difference that this theory has to the explanation of the Isu is that the Isu did not come from outer space, having resided on the Earth and evolved over time.
- However, this theory can be supported by a hidden file in the audio of Assassin's Creed IV: Black Flag, where John Standish gives a monologue sarcastically congratulating the listener for finding said file. In it, he remarks about how much potential outer space has, and how the listener should have become an astronaut. It is possible other Isu members may have shared this view of space.
- During the transcript of Isu history, imagery could be seen of triangles that resembled the logo utilized by Abstergo Industries.
- Although Minerva stated she, Jupiter, and Juno were in charge of preventing the first coronal mass ejection, it has been also said that the Isu were too consumed by the war effort to notice the solar activity, making it seem like a majority of the Isu themselves were entirely unaware of the solar flare that was to come except very few scientists. Whether this is a writing error or the Isu scientists withheld information from the rest of their species is unknown.
- The word Isu is quite similar to the Egyptian word "jsw" which means 'Ancient(s)'. 
- Assassin's Creed (mentioned only)
- Assassin's Creed II (first appearance) (as projecion)
- Assassin's Creed: Renaissance
- Assassin's Creed: Brotherhood
- Assassin's Creed: Brotherhood (novel)
- Assassin's Creed: Revelations
- Assassin's Creed: Revelations (novel)
- Assassin's Creed: The Fall
- Assassin's Creed III
- Assassin's Creed IV: Black Flag
- Assassin's Creed: Brahman
- Assassin's Creed: Unity
- Assassin's Creed: Syndicate (first referred to as "Isu")
- Assassin's Creed: Origins
- Assassin's Creed: Odyssey
- ↑ 1.0 1.1 1.2 Assassin's Creed: The Essential Guide
- ↑ 2.0 2.1 2.2 Assassin's Creed: Syndicate
- ↑ 3.0 3.1 3.2 3.3 Assassin's Creed
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 Assassin's Creed II
- ↑ 5.0 5.1 5.2 Assassin's Creed Encyclopedia
- ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 Assassin's Creed III
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Assassin's Creed: Brotherhood
- ↑ 8.0 8.1 8.2 Assassin's Creed: Unity
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 Assassin's Creed IV: Black Flag
- ↑ 10.0 10.1 Assassin's Creed: Revelations
- ↑ Assassin's Creed: Unity – Database: 15. Precursor Memo
- ↑ 12.0 12.1 Assassin's Creed: Brahman
- ↑ 13.0 13.1 13.2 Assassin's Creed: Project Legacy
- ↑ Assassin's Creed III: Liberation
- ↑ Assassin's Creed: Bloodlines
- ↑ Assassin's Creed: Odyssey – Modern times
- ↑ Assassin's Creed
- ↑ 18.0 18.1 Assassin's Creed: Revelations – Abstergo Files #20
- ↑ Assassin's Creed 4: Hawk
- ↑ Assassin's Creed 3: Accipiter
- ↑ Assassin's Creed 3: Accipiter
- ↑ Assassin's Creed: The Fall
- ↑ "Isu". The Codex. Accessed 8 September 2018.