Thousands of year ago after the Lanteans were defeated in the war against the Wraith, many of their kind decided to return to their home in the Milky Way. These beaten people decided to devote their lives to Ascension and leave the physical plane behind them. However, a number of them opposed this idea and felt that mankind on Earth needed to be guided as well as prepared for the possible threat posed by their distant Ori cousins. Among their number was Lilith, also known as Ninlil or the Creator, who made use of some of her research in the Pegasus galaxy to create a counter to a future Ori crusade.
Using cloned samples of the Wraith, Lilith began merging the DNA with that of Humans at a laboratory on Earth in order to produce a race that would serve as warriors against the Ori in the future. This signaled the birth of the Lilin, who began to prosper in secrecy on the planet. Eventually, Ninlil lost her grip upon reality, but her original intent was the creation of a race that merged the best qualities of the Ancients, Humans and Wraith in order to combat the Ori, thus protecting her people as well as Humanity. In turn, the Lilin respected their makers, whom they called the Annunaki.
However, the other Ancients believed that Lilith had created an abomination and demanded that she destroy her experiments. She refused and was considered a martyr by the Lilin. In that age, they resided in the valley of E'den, which also housed Lilith's other creations as well as her laboratory. A period of climatic changes occurred at this point, leading to increased rainfall and a great flood that destroyed Lilith's lab. This was known as the Deluge and occurred five thousand years ago, nearly destroying the newly emergent race. However, Lilith led them to safety and gifted them with certain technologies in order to survive. The Sumerian King Gilgamesh provided her a sanctuary at Uruk where the Lilin resided. Among the Lilin were also a number of hybrid animals created by Lilith that became embedded in Human mythology as monsters or chimera. While these remained with the Lilin, the creatures were infertile and incapable of breeding, which meant they eventually died out.
The Lilin became divided after Lilith disappeared to Egypt where she was killed by Nirrti and separated into two different cults. One later became known as the Lilith cult, while the other was the Ninlil cult; each had a different interpretation of the mission given to them by their creator. Living amongst Humanity on Earth over the centuries was also not an easy task and the Lilin found themselves hunted and killed for being witches or other demonic creatures.
Over the years that followed, the Lilin bettered their attempt at hiding in Human society. The Ninlil cult began to infiltrated institutions such as travel companies and other such organizations in order to continue funding their lifestyle. Some members of the Ninlil cult subtly aided in the excavation of the Stargate and knew of its location after that event. They also made sure that those of their bloodline survived to adulthood, using their powers to cure of them of various illnesses. The two cults often came into conflict with one another, with the Lilith attempting to exterminate the Ninlil. While this secret war continued, the Ninlil attempted to breed an evolution among their kind that was capable of feeding on animals. The Lilith also continued their practice of feeding on Humans, which drew the attention of the FBI and eventually made Stargate Command and elements of the Atlantis expedition aware of the Lilin race. In the case of the SGC, the Lilith cult targeted Mark Payton, the cousin of IOA member Richard Woolsey. After his death, Woolsey found a tape from a sleep study of Lilin visiting him at night. Doctor Daniel Jackson later learned that this was a member of the Ninlil cult who had been visiting him since childhood, keeping him alive from a genetic condition that would've killed him long before.
Both groups sought the gingko extract from a world in the Pegasus galaxy where the Ancients had established a research post prior to their leaving the Milky Way for Pegasus. This world had been terraformed by the Ancients, who brought large samples of plant and animal life from prehistoric Earth to this world in order to study the traits they thought were needed to reach Ascension. This world was where Lilith had carried out the first parts of her research, but was forced to abandon her work due to the approaching threat of the Wraith. This gingko extract would allow the Lilin to trigger transformations among Humanity, activating the Iratus bug gene in those humans across Earth who possessed it, though their reasons for doing so varied. In the case of the Lilith faction, they wanted to transform those with the bloodline and control the world while summoning the Wraith to help fight the Ori. One of the Ninlil compared this to the Biblical Apocalypse if it happened. In the Ninlil's case they were attempting to breed a cambion that could feed on animals rather than people. They succeeded in the form of an FBI profiler Doctor Rebecca Laurance who was aiding the SGC in tracing the Lilin. One of Ninlil told John Sheppard they wanted to inject humanity slowly with a vaccine made of Rebecca's evolved virus and the ginko which would turn people into Lilin, but with the ability to feed on animals instead.
After tracking the Lilin to a series of caves in Tasmania, the SGC launched an operation to stop them. John Sheppard and Rebecca Laurance were rescued by the Ninlil from a car crash and the Ninlil activated the retrovirus in Rebecca. The Lilith attacked and the Ninlil held them off, aided by Sheppard as Rebecca tried to flee. Following a theory by Rebecca and Doctor Bill Lee, the SGC set up amplifies that would use the cave systems natural harmonics to spread a chant of "Senoy, Sansenoy, Semangelof", believing that there was a reason that mythology stated chanting those names would protect one from Lilith's children. Doctor Daniel Jackson eventually realized it was part of a cantillation which Teyla Emmagan sang. The cantillation reached the Lilin and killed everyone in both factions to the horror of the SGC team who hadn't meant the Ninlil any harm. Doctor Carolyn Lam later determined that Lilith had implanted her creations with a failsafe: exposure to a particular pattern of frequencies, namely the specific sequence of tonal variations in the cantillation caused fatal aneurisms in any Lilin exposed to it.
However, not all of the Lilin were exposed to the fatal chant and killed: Rebecca and eight others survived and boarded a Greenpeace ship for Antarctica. They stole an inflatable boat and escaped towards the Antarctic shore but a monster storm hit soon after and it was unclear if they survived or not. If they did, Rebecca's ability to feed on animals would allow her to sustain herself and the other Ninlil with her. A massive group of Lilith cultists reached the area as well using an Argentinian cruise ship the Verreisen Sie Heim who drew in another nearby ship with a distress call and then fed on the passengers. The cruise ship disappeared towards Antarctica shortly afterwards and its not clear if the Lilith cultists aboard survived the storm either. In case they did, the IOA ordered M1M-316 where the ginko grew destroyed. To prevent this, Atlantis faked the planet's destruction so to everyone it appeared as if the ginko was gone.
The Lilin were a merger of Human qualities with those of the Wraith and some Ancient DNA from Lilith herself, making them hybrid creatures. This meant that they possessed the feeding organ of their Iratus bug ancestors, allowing them to take the life of another living being and add it to their own. Beyond this, they were indistinguishable from Humans, though there was pallid, almost bordering on albinism. The original intent of Lilith was to make the Lilin capable of feeding on animals, thus freeing them from using their abilities on Humans.
They had the standard lifespan of a Human but were capable of enhancing their lifespan indefinitely by feeding. They also possessed a form of genetic memory, allowing them to witness events that occurred long before their birth. Furthermore, they were able to use their telepathy to form a mind-link to communicate with one another. They were also capable of using this ability on Humans to learn their dark secrets or sense their moods.
The male are known as Incubi while the female are called Succubi. Both are incapable of breeding with one another but are able to with Humans. These children are called Cambion; they are more Human in appearance and watch over them while they infiltrate Human society. While typically the Cambion served the Lilin, there were cases where some individual Cambions were not aware of their heritage. Even these served a purpose as they spread their genes among the Human race, thus ensuring that their kind maintained sufficient numbers. Sometimes, in times of great starvation, the Succubi and Incubi were known to feed on the Cambion to sustain themselves.
- This meant that the Incubi and Succubi were incapable of breeding more of their kind except through the Cambion.
The race are divided into two cults, with one designated by the SGC as the Lilith sect and the other known as the Ninlil sect. The former are considered the predatory version and seek a "divinely promised" destiny: dominion over the Human race. Thus, they believe in the Great Battle, an outright war against the Ori, with victory being the chance to achieve their destiny. They also perform a ritualized form of organ removal on their victims. The group misinterpreted the intent of their creator and instead evolved a set of behaviors that were peculiar to them. Before this event, they waited for the Awakening, which was when their Cambion offspring spread their bloodline among the Human race to such an extent that they all rose up to take their place for the coming war. This group also made extensive purges among their kind to eliminate the other cult, as they believed that they were weak and were heretics. Ultimately, the Lilith group believed that the Pegasus galaxy was their spiritual home and thought to return to it in order to bring the Wraith to the Milky Way galaxy to battle the Ori.
The Ninlil sect by contrast wished to help their Human cousins. Members of this cult sometimes made use of their feeding organs but not maliciously. This meant that they performed the feeding on those who were in pain and required a merciful death. The practitioners of this faith believed that it was their sacred duty to protect all sentient life from the Ori, believing themselves to be instruments for the achievement of a specific end. Its members also attempted to breed a Cambion amongst their number that had an adjusted form of the Iratus bug retrovirus, which would develop the capacity to feed on animals. They do not consider themselves a religious movement and only take in those members whose memories are lucid enough for them to know the truth of their heritage. Its Watchers protected those of their number that were unaware of their bloodline.
Lilith had given the Lilin a religion that stated that they were the descendants of the Wraith from the Pegasus galaxy and that their sacred duty was the protection of the Milky Way from the Ori. The term "Awakening" was applied to those Lilin that learned the truth of their ancestry and their creation. The Lilith cult believed that the ginkgo extract should be used to awaken all those Humans with the bloodline, with the rest of Humanity being sacrificed to feed the newly developed Lilin, who would thus wage war against the Ori and their followers. They ultimately saw themselves as weapons bred for war and instruments of the Ancients, which was a concept shared by the Ninlil group. The Ninlil group on the other hand believed that Lilith always intended them to feed on animals. As a result, their plan was to create a vaccine with the blood of one of their number who's virus had adapted to allow her to feed on animals and ginko extract to Awaken people with the ability to feed on animals instead of people. This would be done slowly and controlled. This was also a two-pronged process as the Awakening signaled all Lilin to come out of hiding at once. One of the Ninlil told Doctor Daniel Jackson that Lilith had taught them that one of the Annanauki as the Lilin knew the Ancients would "descend from the Heavens" and take on human form to lead humanity in the Great Battle. The man believed Doctor Jackson himself to be this person: while not an Ancient, Daniel had Ascended and returned to mortal form. He also played a major role in the war with the Ori and was later responsible for their destruction.
Among their kind exists the position of Watcher who serves as a high priest while the first generation of Cambion serve a role that was equivalent of a Wraith Hive Keeper. They made use of caves and chambers known as Sanctums where they gathered among their own kind.
When Lilith created the Lilin, she implanted a failsafe in them: the exposure to a particular pattern of frequencies, namely the specific sequence of tonal variations in the cantillation of "Senoy, Sansenoy, Semangelof" caused fatal aneurisms in any Lilin exposed to it. (SGA: "Blood Ties")