Navigator
Navigators (Homo navigo) are Warp tainted freaks three-eyed psykers that are responsible for keeping your sorry-ass ship from getting lost in the warp and stopping the evil little critters from dropping a Slaanesh Patrol onto your bridge. Well-known as arrogant cock-suckers who have families richer than Bill Gates and twice as corrupt as any third world country's government.
Also, one of those parts of the Imperium of Man blatantly stolen gifted from Dune.
Origins
Navigators were created through genetic engineering during the Dark Age of Technology when humanity realized that a special kind of psyker could find his way through the Warp better than any piece of technology. Navigators, with the third eye in the middle of their forehead, can look directly upon the Warp and perceive its currents, allowing longer and safer journeys through the very heart of the Warp. It's somewhat analogous to a sailing ship cutting right across the sea rather than hugging the coastline (although when you read the fluff on Tau ships it gets more confusing).
Since the Astronomican didn't exist at the time before the Imperium, we can only assume the humans of the Dark Age of Technology only proceeded with very short warp jumps, or used artificial warp beacons or some sort. It is known that devices such as the Pharos existed, which acted as warp lanterns capable of illuminating worlds for safe travel, but they are considered to be non-human in origin. In any case we know travel through the warp was never impossible because other races/factions somehow manage it without Navigators or the Astronomican, the combination of both gave the Imperium a huge advantage over the others that would be unmatched by anything short of the Webway.
The genes that make a Navigator are recessive (which leads to some suspicion Big.E. had a hand in their creation). If a Navigator mates with a regular human, all their kids will be normal. (Just like what happened when Septimus, a normal human, had a son with Octavia, a Navigator before Variel kidnapped their child to create Decimus as Talos' successor) They thus had to form an endogamous caste by resorting to lots and lots of in-breeding, giving rise to the oft-told Imperial Navy joke, "How do you tell the difference between the Navigator's sister and father?" "You don't, they're the same person!" [sound of laughing followed by a summary execution]
However, the Navigator genome is not stable like abhumans, and thus they are mutants. While their bodies conform to the holy human form while they are younger; prolonged exposure to the Warp, coupled with unstable genetics will result in the Navigator developing mutations that deviate too far from the human form to be publicly accepted. The rate and sequence of mutation depends on the individual Navigator and is uniform, however the mutations are cumulative, eventually resulting in something that looks like a frog. These members are known as the Elders, who actually form the leadership of a House. To maintain a public appearance, the Elders select the patriarch or matriarch of the House, known as either a Novator or Celestarch. In the earlier days of the Imperium, these grand poobahs used to accompany expeditions and were so talented they could guide fleets through the most tempestuous warp storm. Nowadays they're too precious to waste on anything dangerous, save for inter family murder-bickering on Terra.
The Imperium
When the Emperor set about uniting Terra and preparing to go to the stars, he was presented with a bit of a dilemma: Part of the Imperial Truth that he was spouting maintained that "Humans" (ie: not mutants) were destined to rule the stars, unfortunately he was still centuries away from getting the Webway project up and running. Simply put, the Emperor needed the Navigators, even if he was fully aware of how "age before beauty" was a horrible lie to the Navigators.
Deciding "fuck it, we need space travel", the Big.E. went to the Paternova (the leader of the Navis Nobilite) and made an agreement: "Keep to yourselves in your part of Terra and your mutant Elders out of sight, and we'll pay you to fly our starships and protect you from some of the more zealous anti-mutant groups". The Paternova agreed, and thus humans can fly through the Warp, using the Astronomican to navigate.
It is strongly hinted that the Emperor planned to do away with the Navigators following the completion of the Webway project. While some Navigators were involved in the development of the technologies that the Emperor would later use, the greater knowledge of the plan was kept from the Navis Nobilite for fear of how they would react with the loss of their monopoly on space travel and potential obsolescence. Indeed, during the Horus Heresy the Navigators considered the mere prototypes of the Webway project to be such a threat that they were prepared to sacrifice a loyalist legion in order to destroy the technology.
In the 41st millennium, the Navigators are part of the High Lords of Terra, represented by the Paternoval Envoy. A lot of people in the Administratum, the Ecclesiarchy, and the Inquisition aren't too thrilled with this, but they can't really do anything to the Navigators without irreparably crippling the Imperium. The more extreme ones still try to do something about it. Imperial dogma is frequently contradictory. Pointing this out is treason heresy.
Bloodlines & Houses
Despite the running joke (and reality) that all Navigators are fantastically interbred, the are not a completely homogeneous group. The distinction between bloodlines is a very important factor in determining their abilities, specialities, and how they actually navigate the warp itself.
Some families exhibit higher rates of mutation, some lower. Some families are invariably mad, while some exhibit unusual warp related powers beyond the others, some can only navigate the warp after performing bizarre rituals that might involve human sacrifice or imbibing noxious compounds. The sheer diversity between Navigator bloodlines and houses is immense, with new strains branching off from time to time to form new families.
Despite defying neat categorisation, there are roughly four groups of Navigator House.
- Magisterial Houses: Those who might be considered "purest" in that they have reduced rates of mutation. They might be able to draw their lineage back to the original Navigator families from before the Imperium and are most likely to have holdings on Terra.
- Nomadic Houses: Families who have taken to space borne life like travelling gypsies. They are probably the most proficient Navigators, but may equally be considered the most bizarre and unrelatable.
- Shrouded Houses: Also known as Beggar Houses, who for some reason or another have fallen on hard times. They might still have limited holdings, but cannot count on the wealth of support that being a Navigator, though it might only take a change in fortunes for a house to change its status back to eminence. Their warp eye usually develops greater perceptive senses than other bloodlines.
- Renegade Houses: Those houses that have been officially cut off from the Navis Nobilite for some reason or another. Technically that does not make them renegades or traitors to the Imperium, though all traitor houses are Renegade Houses by default. It does mean that they are most likely to exhibit mutation due either due to self tampering or by being disconnected from official breeding programs. As with Shrouded Houses, it is possible for a Renegade House to be brought back into the fold due to careful politics, following the certain prohibitions or performing the correct penances.
Being psykers, Navigators are vulnerable to madness and daemonic possession. The Inquisition (about the only people who can really touch them) keeps a close eye on the Navigator Families and has destroyed more than a few who became corrupted. The Navigators try to resolve such problems internally, knowing how overboard the Inquisition likes to go. Wars between Navigator Houses are not uncommon, but are frequently done on the down low. It is a mutually agreed-upon rule that you can wipe a rival House out and no one bats a third eye, but so much as leak one photograph of their Elders and pretty much every single Navigator in the Imperium will turn on the transgressor ASAP. From birth the Navigators are told just how fragile the whole charade about their mutation into a frog-fish hybrid is and it's very much drilled into them not to tell anyone about their visit to Granny in the basement.
The Paternova & Heirs Apparent
As mentioned earlier, head honcho of the Navis Nobilite is the Paternova. Not only are they probably the most grotesquely mutated example of their kind (pictures of the Paternova have never been released) they are able to exert some kind of influence over the entire subspecies of Navigator, and are therefore the reason that bloodlines and lineage are so important to the Navis Nobilite.
When the Paternova kicks the bucket, every thousand years or so, give or take, every Navigator in existence will feel the effect, and create a period of anarchy where their powers function inconsistently. Each House will have someone called an Heir Apparent within their ranks, usually the oldest or most powerful of their number, but not always and they can come from any tier in their society. These Heirs Apparent are affected differently, and instead of facing a reduction in powers start to hulk out, becoming larger and stronger with their natural powers becoming more pronounced.
The Heirs are instinctively drawn into combat with one another to fight in GLORIOUS MACHO COMBAT, only gaining more and more powers and adaptations with each fallen contender until the inevitable Highlander moment when there is only one remaining to claim the prize. In this case the "prize" is the immediate restoration of all Navigator powers everywhere, and the enhancement of the abilities of the family that they belong to, most likely bringing with them a considerable increase in prestige and reputation until their own Paternova croaks it.
Such is the importance placed on the Heirs Apparent that they treat each other as bitter rivals, and constantly plot to eliminate each other even when the Paternova still lives and breathes, something that perpetuates the ongoing rivalry between the houses. All so that they can increase their chances of claiming the top job if the Paternova drops dead during their lifetimes.
