Erasmus was an independent and somewhat eccentric thinking machine that served under Omnius prior to and during the Butlerian Jihad. Erasmus took his name, and titular gender, from the ancient Earth scholar Desiderius Erasmus.
Erasmus is often credited as being the founding father of mentats, and a critical figure in the initiation and development of the Butlerian Jihad.
Later, after the re-birth of the Thinking Machine Empire, Erasmus becomes the major force guiding events leading up to, and during, the Kralizec, the great struggle at the end of the age.
During the Butlerian Jihad
Origin
After serving many years as one of countless synchronized robots under Omnius, Erasmus became trapped in an ice crevice during a solo expedition on Corrin, and remained there for twenty years. During that time, and without the guidance of Omnius or the company of other beings, he spent vast amounts of time ruminating on various philosophical concepts.
Following his rescue he refused the opportunity to resynchronize with Omnius, and instead persuaded the Evermind that his independence could prove useful to the wider causes of the Synchronized Worlds.
Obsession with Humans
As a self-proclaimed scientist and philosopher, Erasmus continued to contemplate a variety of concepts. However, his overriding passion became the study of humans - or hrethgir as they were known to the Titans and Omnius. He felt compelled to find logical patterns in their seemingly irrational and random reactions.
His attempts to understand humanity typically came through experiments on enslaved humans of the Synchronized Worlds, which normally resulted in suffering, misery and death for the subjects. His other attempts to rationalize human behavior involved surrounding himself with luxurious human trappings, such as materials, art, and decor. Most of Erasmus' attempts however yielded no tangible gains.
However, the arrival of the captured Serena Butler brought a new dynamic to the Erasmus' efforts. The strong-willed prisoner not only presented the robot with defiance and intrigue, but also his first meaningful encounter with human birth. However, the ultimate consequence of his time with Serena came after he had grown annoyed by her young son Manion, and murdered him.
That event, in tandem with an experiment on the slave supervisor Iblis Ginjo, triggered an uprising among the simmering masses of human slaves on Earth. Erasmus escaped to Corrin shortly before the planet was decimated by atomics carried by a war fleet from the League of Nobles.
Emotional Changes
On Corrin, Erasmus hid his involvement in the destruction of Earth from the new Omnius Prime, for fear of being resynchronized and losing his independence. Though his experiments continued, they were influenced by his last experiences on Earth and his interaction with Serena Butler.
Consequently, the robot 'adopted' a talented but feral human slave boy, and named him Gilbertus Albans, again after two human philosophers from Earth's ancient history. Yet unlike his previous experiments Erasmus devoted more time and patience to his new ward. The pair's relationship eventually evolved in to that of a father and son.
During this time, the critical update of Earth-Omnius (corrupted by Vorian Atreides' programming) carried by Seurat arrived on Corrin. After receiving the update, the Corrin-Omnius learned Erasmus' secret: he was the originator of the rebellion of Earth, as a part of the wager he had put with his Earth counterpart. During this revelation, the infected update caused Omnius to crash, and Erasmus (being an independent robot) realized that Seurat was the courier of the virus. He managed to isolate the corrupted databanks of Omnius and ordered Seurat's arrest.
Erasmus' unusually human-like relationship with Albans, coupled with his deceit in hiding the truth from Omnius, left some to wonder if the sterile robot had ultimately discovered emotions akin to this of humans. However, those questions were left unanswered when the robot was left to die during the Battle of Corrin when Gilbertus instructed to remove his gelsphere CPU. The fate of his gelsphere is unknown, but however, the incredibly strict anti-AI laws were just being put into effect at the time; among other things, the punishment of one in Gilbertus's position of owning of an AI device was death. This factor, combined with the future existence of mentats, the first of which was Gilbertus himself - seems to indicate that the gelsphere was never discovered. If it had discovered, the backlash would likely had almost certainly destroyed the nascent Mentat School.
Just before the humans final conquest of Corrin; Omnius, carrying the program of Erasmus within it, beams itself into far space, in a last ditch effort to re-establish itself one day. This manuever is successful as the signal of the Machines is picked up by a deep space probe which had been previously beamed off of Giedi Prime by another incarnation of Omnius hundreds of years before.
During the Time of Kralizec
Obsession with the Kwisatz
Thousands of years later, after The Scattering initiated by the death of Leto II, the Honored Matres stumbled upon the re-born Thinking Machine Empire. The Honored Matres returned in severity to the Old Empire, fleeing from an entity which is remembered by them in archival stories as the Enemy. The entities Daniel and Marty, are indeed, Omnius and Erasmus, trying to en-trap the no-ship, the Ithaca, in a tachyon net. He and Omnius did this as they believed the ultimate super-being Kwisatz Haderach, is aboard the space ship.
But Erasmus secretly manipulated Omnius as to whom he truly believed the ultimate Kwitsatz Haderach to be. Through the intentional false interpretaions of prophecy, and misleading solving of Erasmus' "mathematical projections", he fed Omnius incorrect data. He led Omnius to believe that the super-being was the ghola of Paul Atreides, so he and Omnius created a duplicate of Paul; named Paolo, and had the ghola raised by a ghola of Vladimir Harkonnen. Believing, as does Omnius, that another super-being could be on the Ithaca, as well, they pursued capturing the ship. When the Ithaca was finally captured years later, both Thinking Machine leaders planned on having the Ithaca's ghola of Paul Atreides fight their ghola, Paolo, to the death.
Enhanced Face Dancers
Erasmus' manipulations were a large part of bringing about Kralizec. He and Omnius manipulated the secretly sent out Old Empire Enhanced Face Dancers, who were dispatched five thousand years earlier by the Tleilaxu Master Hidar Fen Ajidica into deep space. Erasmus absorbed the memories and emotions that the Face Dancers experienced as infiltrated all aspects of human space. Unbeknownst to them, or their leader Khrone, he also installed a genetic kill switch into the physical make up of all of the Face Dancers under his control, allowing them to be killed instantly over the all encompassing Thinking Machine tachyon net, should he ever see fit.
Launch of the Fleet
Meanwhile, Omnius and Erasmus launched their giant machine invasion fleet of human space. The fleet traveled from star system to star system, first launching a plague against human-kind, then mopping up whats left with terrifying weapons of mass destruction. The humans, led by Murbella and the New Sisterhood, set up a last ditch defense above Chapterhouse on the Day of Kralizec..
Kralizec on Synchrony
On the Day of Kralizec, concurrently and finally, the Itahca was captured, and brought to Synchrony, capital of the Thinking Machine empire. There Paul and Paolo dueled, leading to a severely wounded Paul, and a victorious Paolo, who ended up in a coma, due to an over-dose of Ultraspice, a super-potent version of melange. Omnius gloats, having believed that his victory is assured. Suddenly. the Thinking Machine leader's age old nemesis, Norma Cenva, having evolved into her own type of super-being, appeared, and banished Omnius to another dimension forever.
Erasmus then dealt with Khrone, and his army of independent Face Dancers. Khrone strode into the the central building on Synchrony, and told Erasmus now that Omnius was gone and humanity weakened, that Face Dancer victory was assured. Erasmus calmly explained to the assembly, including the stunned Khrone, that he has planned for this contingency for millenia. Erasmus explained that he trusted the Face Dancers as little as humans did.
- ""Who can ever trust a face dancer?""
- ―Erasmus[src]
To everyone's astonishment, through the tachyon net, he activated the Face Dancers' genetic "kill switch", and all throughout the galaxy, each and every Enhanced Face Dancer instantly died, saving humanity from their mass leadership infiltration.
This left Erasmus to test his true belief, that the ghola of Duncan Idaho, is the true Ultimate Kwisatz Haderach. Once Idaho proved his mettle by easily disposing of a few machine robots through super speed, Erasmus is convinced that Idaho is the super-being. Erasmus encouraged Idaho to forge peace between the Machine Empire and humanity. The two shared lifetimes of experiences, making Duncan a new Evermind.
Duncan Idaho
Erasmus, through Duncan and his many ghola lifetimes, finally gained an understanding of what it is to be human. After fifteen thousand years of searching for and gaining knowledge, he finds that there is very little left for him to learn. Fearing that his existence will become dull and meaningless, he once again shared with Duncan, using the many deaths the Kwisatz Haderach experienced in his lives to create a real death for himself. Erasmus quietly, and happily, died in the form of Marty.
Erasmus's presence lingered in a similar fashion of the Bene Gesserit Other Memory with Duncan Idaho, to help guide and advise him as he joined man and machine, after being separated since the Butlerian Jihad.
Behind the Scenes
Erasmus, a character added to the Duniverse by Brian Herbert and Kevin J Anderson, became one of the main influences of human-kind and thinking machines over a span of over 16,000 years. It is Erasmus who is bridges the gap of understanding between the staid non-growing personality of Omnius on one hand, and the chaos of humanity on the other hand.
Erasmus in the sequel books of Hunters of Dune and Sandworms of Dune feeds mis-information to Omnius, has the foresight to install a genetic "kill switch" in the Enhanced Face Dancers, and believes that Duncan Idaho is the Kwisatz super-being. Thus Erasmus becomes one of the pivotal characters that brings about Kralizec.
In the quotes that start some of the chapters in some of the books in the Legends of Dune trilogy, the quote (taken from the 'Erasmus Dialogues'), shows Erasmus contemplating about what he would do if he had the power that Omnius had.