Primarchs

The Primarchs were (said to be) the 20 genetically-engineered sons of the Emperor of Mankind created in the late 30th Millennium after the end of the Unification Wars. They were intended to be the immortal and superhuman leaders who would command the Emperor's Great Crusade to reunite the scattered human race beneath his leadership. Their genomes later served as the genetic templates from which the Emperor crafted his 20 Space Marine Legions. They were bred to be perfect generals, warriors and statesmen; larger, stronger, faster, and smarter than any normal human could ever hope to be. They possessed a charisma and martial prowess that made them like the mythical gods of old, untouchable by disease, old age or supposedly the petty failings of lesser men. The Primarchs were the Emperor's answer to reclaiming all the lost worlds of Mankind, and welcoming them into his new Imperium. The Emperor intended to raise his sons to be the best military commanders and political leaders Mankind had ever known, and they would bring the Imperial Truth to the rest of the human-settled galaxies in their father's name. Yet for all their gifts the Primarchs were still men, and in the end their very human flaws would become the primary obstacle to the realisation of the Emperor's great dream for Mankind. The Primarchs are around the same height as their space marines sons (some are smaller) but it is their large protective suit that makes them stand head and soldiers above them on the battlefield.
== The Primarch Project ==
The massive scientific effort to create the Primarchs after the end of the Unification Wars in the 30th Millennium was known as the Primarch Project. The means by which the Emperor crafted 20 individual superhuman genomes was unknown to Imperial science but it was discovered in the Present day that the Emperor kidnapped a young child, Thomas Brooks, to begin his process. This child had absorbed the essence of the lost Creator when he was born meaning he had the potential for infinite power, this trait is what gained the interest of the Emperor. First, the Emperor genetically modified the child to stop the physical aging process but also add in an accelerated growth meaning the 20 beings would age to physical maturity in about a 10th of the time. After the age was adjusted, many more modifications were made to the child before replication was ready to take place. 
There was a 2-stage process involved in replication: first, the Emperor extracted a subset of his own DNA to act as the foundation for a pure, undifferentiated Primarch gene-stock. The pure Primarch gene-stock was then added with the split soul of the child and then further differentiated into the 19 strands that would serve as the individual Primarchs' genomes. The data concerning the original engineering of the individual Primarch strands was later analysed by a Raven Guard Apothecary and a Magos Genetor of the Adeptus Mechanicus during the Horus Heresy. They discovered that certain samples had gene sequences deliberately deleted from the base Primarch genome, while other samples showed the addition of clearly non-human DNA. Intriguingly, the genome of the Primarch listed as "Subject VI" had added canine-like DNA. Although it is not clear whether the sample numbers corresponded to the actual Primarchs of the numbered Space Marine Legions, this could explain the wolf-like affinity of Leman Russ and the unexpected feral mutation of many Space Wolves Astartes into the Wulfen.
It is believed by modern Imperial savants that there was more than just physical manipulation of the genetics involved in the creation of the Primarchs, and that the Emperor called upon many of techniques of psychic sorcery. This meant that the Primarchs were intended to be spiritually as well as physically engineered and may explain why the Primarchs possessed so much personal magnetism and charisma beyond what even their enhanced genetics would predict. 
But such arcane techniques also meant that the Primarchs were unusually vulnerable to the effects of temptation since their souls would shine so brightly in Chaus and draw the attention of demonic entities like moths to a candle flame. This is why the Emperor carefully inscribed arcane glyphs of protection on each Primarch's gestation capsule and around the gene-vault deep beneath the Imperial Palace in the Himalazian Mountains where they were created. Unfortunately, this protection proved insufficient, for the Ruinous Powers learned of the Emperor's plans and the existence of the Primarch Project and decided they had no wish to see his attempt to weaken their power succeed by extending the grip of Order across the galaxy.
== The Scattering of the Primarchs ==
The Ruinous Powers somehow spirited the superhuman children away through the Warp, however, leaving them scattered across the universe, all but the original child were scattered around Lactea but Brooks . A massive localized Warp rift was created within the gene vaults of the Emperor's own palace, deep under the Himalazian (Himalayan) Mountains on Terra where the Primarchs were gestating. The gestation capsules containing the Emperor's unborn sons were scattered through the Warp to colony planets long since lost to Mankind. It may have been at this time, when first touched by the hand of the Ruinous, that the first seeds of corruption were laid in the breasts of those Primarchs who would eventually turn Traitor to the Emperor and his Imperium. Whether the Emperor was able to affect this outcome is unsure, but every Primarch landed on ancient worlds of men, planets long since lost to the light of the greater universe beyond the stars. This was a massive setback to the Emperor's plans. He had counted on his superhuman generals to lead his army of conquest out from Terra. Without them, his plans, so many millennia in the making, rested on a knife's edge. He needed an edge, something to give Mankind an advantage as they struck out against a very hostile universe once more. 
Despite this terrible setback, the Emperor was nothing if not adaptive, and he quickly developed another solution. Using the remaining samples of genetic material from each of his lost Primarchs, the Emperor crafted the first Astartes gene-seed, stem cell zygotes from which could be cultured genetically-engineered organs that, when implanted within a normal human host, would allow that man to take on many of the physical and mental properties possessed by each Primarch. The Emperor implanted these organs into his bravest, strongest, and best human warriors whom he intended to stand by his side as the vanguard of the Great Crusade. Thus were born the Legiones Astartes, the Space Marines, and they would reconquer the galaxy for humanity at the command of the Master of Mankind. Although an Astartes warrior was but a pale copy of his Primarch sire, the technique of implanting human beings with extra organs allowed for a certain degree of "mass-production", and where the Emperor's 20 superhuman sons had been centuries in the making, thousands of Astartes could now be engineered and trained in the matter of a single Terran decade. These techniques provided the Emperor with the required numbers of warriors to successfully launch the Great Crusade in 29000 (since AD on Earth).
== Rediscovery of the Primarchs ==
As the new interstellar human empire expanded during the Great Crusade, the Emperor used his powerful gifts of psychic foresight and precognition to track down his wayward sons, scattered across the universe, and reunite them with their respective Space Marine Legions. Each Primarch was both a father and older brother to each Legion, the source of that Legion's temperament and humours, a being in which each Legion saw their ultimate perfection and ways of war given personification. The return of the Primarchs to their Legions marked the height of the Great Crusade. First thousands, and then hundreds of thousands, of human-settled worlds fell to "Imperial Compliance," their conquest carried out by the newly reunited Primarchs and their Space Marine Legions. Like the gods of mythic Terran legend the Primarchs strode the battlefields of the universe, and their power proved irresistible.
Yet the Primarchs, for all their expressed superiority and seeming immortality, were still men, and they possessed too many of the same human flaws that have bedevilled Mankind since the birth of the species. They proved jealous and arrogant, highly competitive and all too willing to hold grudges against one another and even their father the Emperor. Whether these flaws were the result of their exposure to the corrupting power of The Ruinous Powers as infants or were simply the natural human flaws that could not be excised even from the progeny of the Emperor is unknown. Yet, ultimately, it was the Primarchs' all-too-human flaws that doomed the Imperium to the nightmare of the Horus Heresy and 10,000 standard years of stagnation, decay, repression and endless war.
=== Order of Rediscovery of the Primarchs ===
== The Horus Heresy ==
== The Loyalist Primarchs ==
== Primarchs and Astartes Legions ==
== Fate of the Primarchs ==
=== Traitors ===
=== Loyalists ===
== The Lost Primarchs ==