Martin's species

Martin's species are unnamed sapient brood parasites who colonized Earth, disguising as real estate salesmen and kidnapping Humans to use as surrogate parents for their young.

Biology
Physically, Martin's species appear nearly identical to Humans. Their only physical distinction from Humans are two throat sacs that can bulge out from their necks when uttering their native language, and are seamlessly merged with the rest of their body otherwise. While no females of their species have been sighted, their species appears to be viviparous, and it is possible that females of Martin's species are identical to Human females in every aspect except for their throat sacs. Notably, their lifespans appear incredibly short, only lasting for an estimated one year, causing them to physically age rapidly. After three months, they physically grow to resemble a ten year old child, and after about four months, they have aged into adulthood. Their minds and mental maturity appear to age at a similar, if not faster rate, possibly stimulated by alien transmissions broadcasted through televisions, and gain an adult-like voice since the early stages of their lives. They appear to be suited to an Earth-like environment, and are omnivorous, although the food they eat is tasteless. Instead of crying, their young will scream uncontrollably until they are given what they want. Their bodies are also known to be more durable than Human bodies, as young members of this species can survive a blow to the head from a pickaxe dealt by an adult Human with only a minor injury, and seem to feel no pain. While "Martin" appeared to possess super strength when he literally rolled up the body of his dead predecessor, it is also possible that the bodies of Martin's species becomes very fragile near the end of their lives. When threatened, this species is known to be able to run on all fours to easily outrun Humans. Another incredibly notable trait is their tendency to mimic others, replicating their voices and actions near-perfectly, a trait that appears to be almost instinctual, although older members of this species are better at suppressing this instinct.

Culture and society
Little is known about the society of Martin's species. It is known that while they are capable of viviparous reproduction, they currently utilize artificial insemination for reproduction, at least in some part of their society, as shown in a book The Boy received from other members of his species. They also utilize an unknown language which consists of intricate letters, and are known to broadcast bizarre imagery of black and white zigzag lines that appear to be capable of communicating unknown messages to their young. The most notable part of their society is that they are brood parasites, utilizing members of other species, such as Humans, to raise their young until adulthood, for unknown reasons. On Earth, this is achieved through a public front that takes the form of a real estate agency known as Prospect Properties, selling homes in a suburban development known as Yonder. Yonder is filled with identical copies of a green two-story house, fully stocked to sustain a family of three, with identical clouds lazily floating through the sky, creating a surreal and seemingly perfect visage of a neighborhood. Human couples are tricked into entering Yonder by the real estate agents, who lure them in with promises of low prices for a seemingly perfect home, and then strand them within the infinitely stretching environment. The Humans are soon given an infant of Martin's species, with a message telling them to raise the child to be released. The surrogate parents are seen as nothing more than assets to be disposed of upon completing their purpose, with no member of Martin's species showing remorse over their deaths. In fact, Martin's species appears to show little to no remorse or recognition for dead members of their own species, as "Martin" mechanically disposed of his predecessor's body before immediately assuming his post, nor do they show many other emotions in general, often just crude mimicries of Human emotions.

Developing members of their species are occasionally visited by adult members by the third month of their lives, and routinely meet with these individuals when they become young adults, presumably to prepare them for a career of luring more Humans to Yonder. When an acting member of Prospect Properties' offices dies, they are immediately replaced with a new, younger member of their species, and this cycle appears to be well-imbedded in their society, to the point that the aging members are acceptant of their deaths and readily hand over their name tag to their successors. When threatened, Martin's species has been seen running or otherwise trying to escape, not physically fighting back, and do not intervene if the Humans become violent towards the young of their species. They are not seen utilizing any distinctly advanced or alien technologies other than their pocket dimensions, at least not in front of Humans, and appear to have no army or simply no intention of launching a direct invasion of a planet. Male members of this species who are involved in Yonder all dress identically since a young age, with a white dress shirt, black pants, black shoes, and an identical haircut, with adults wearing a black tie. While unnamed for most of their lives, or at least bearing a name they never reveal to Humans, they all take on the name of "Martin" when they take up the mantle of a Prospect Properties agent. Tasteless food and other amenities needed to survive in a relatively comfortable way are regularly delivered to the Humans, and waste is also taken away. All items delivered to Yonder are rather featureless and generic, usually marked with a plain label and the logo of Prospect Properties. Only male members of Martin's species have been seen in Prospect Properties' offices and being raised by Humans, possibly implying that the society of Martin's species, or at least their colonization effort, is male-dominated.

Technology
Martin's species appears to primarily utilize the technology of the worlds they colonize. On Earth, this included automobiles, vacuum-sealed packaging, and televisions. However, they have access to what could possibly be some form of incredibly advanced technology capable of creating pocket dimensions with altered realities. Said pocket dimensions appear to be an infinitely stretching expanse of a suburban neighborhood, which is filled with identical copies of a green two-story house, appearing to be a regular-sized neighborhood from outside. While Humans can enter Yonder freely, it is impossible for them to escape, as any attempt to leave will simply loop them around to the house they were taken to, designated as 9. Travel between the different levels of the pocket dimension, each identical and holding a different Human couple raising more members of Martin's species, is achieved through an impossible structure which appears to be some sort of interdimensional hub, which seemingly emits sounds that can be heard after digging through the lawn of a house for a sufficiently deep distance. This hub is accessed by literally lifting up the sidewalk and sliding in, something that could be only done by members of Martin's species through unknown means, possibly a biometric lock that only allows access to Martin's species, although a tool can be used to prop open the entrance long enough for other species to enter, showing that the structure has no security system other than the looping streets and biometric locks. In addition, members of Martin's species can leave Yonder at will, possibly through a similar biometric security system that allows them to exit the loop. The interdimensional hub, for an unknown reason, was known to display other houses in hues of green, red, and blue, and caused a Human who entered it to sink through the floor in order to pass through the different levels, although the color hues could simply be a visual distortion possibly caused by the hub or the act of interdimensional travel being harmful to Humans. It is also unknown if any other methods of accessing the hub exists, although the Human, Gemma, literally sinking through the walls of one dimension to arrive in the next strongly implies that there is. The grass on the lawn of the houses appears to be artificial, instantly disintegrating when touched by a lit cigarette, but able to regrow after a short time, assuming that the soil remains smoothed out. The soil is also a small layer over a larger layer of a clay-like substance, which appears to be toxic to Humans if they are exposed to it for extended periods of time. Houses appear to quickly regenerate from any damage, such as fire. Martin's species also appears to have unlocked teleportation technology, able to teleport boxes of supplies to the Humans and teleport boxes of waste away.

History
At an unknown point in time, Martin's species colonized Earth. They began to use Humans as surrogate parents for their children, and to achieve this, they created a dimension known as Yonder, which could trap Humans in an endless expanse of identical suburban houses, and created a real estate organization known as Prospect Properties as a front for the operation. The agents present in the Prospect Properties offices, members of Martin's species, would take on the name of Martin, and only one would act at any given time, presumably per location. They would lure in Humans with a seemingly perfect offer of a low-cost luxurious home in a seemingly perfect neighborhood, only to trap them in Yonder and force them to raise their children. When the child is mature, the surrogate parents would be disposed of, presumably killed directly by unknown means if they haven't already died of some other cause, and buried deep under the lawn of the sole inhabited house of each level. The house would then be reset for the next couple. In the early 21st century, a young couple, a schoolteacher named Gemma and a handyman named Tom, traveled to Prospect Properties in search of a home. Martin, greeting them in a strange manner, insisted on taking them to see Yonder, and they complied. He shows them around house number 9, and mimics Gemma when she says she has no children. While the couple observes the backyard, Martin leaves, stranding them in Yonder. After attempting to escape and burn down the house, a nameless infant of Martin's species is deposited on the road with instructions to raise him in order to be released. After 98 days, the boy has grown to resemble a ten-year-old, who speaks with an adult-like voice, mimics Tom and Gemma, and screams when he needs something. After failing to see who comes to collect the waste they leave on the street, as it is merely teleported away, Tom attempts to dig a hole, hoping to break through the dimension, gradually becoming withdrawn as the boy watches alien transmissions through the television. Tom attempts to starve the boy by locking him in the car, hoping that whoever runs Yonder would come to intervene. However, no one comes, and Gemma's maternal instincts prompt her to rescue the boy and raise him. One day, older members of Martin's species meet with the boy in an area unseen to Gemma and Tom, giving him a book in their language, which bore imagery of their species' true form and reproductive method, with instructions not to tell the surrogate parents where he got the book from. However, Gemma tricks the boy into revealing his alien nature by asking him to pretend to be the men he met, making the boy replicate their language with his throat sacs bulging out, causing Gemma to grow fearful of him, continuing to claim that she is not the boy's mother. She and Tom later lock themselves in their room to avoid the boy, who has become a young adult as time went on. Tom has become sick from exposure to the alien clay in the hole, and the boy routinely leaves, with Gemma unable to follow. Tom keeps digging and finds a Human body in a vacuum bag, and then discovers that the boy has locked them out of the house. Tom soon dies of his illness, and is disposed of in a vacuum bag that the boy brings. The next day, Gemma attempts to kill the boy with a pickaxe, but only wounds him, causing him to run on all fours to the sidewalk and lift it open, escaping into the interdimensional hub. Gemma props the entrance open with her pickaxe and follows, being phased through multiple layers of Yonder, seeing each with a different color tint and seeing more Humans trapped in Yonder, forced to raise more children of Martin's species. Gemma, now near-death, is then ejected from the hub, back into number 9, where the boy cleans the house and then zips Gemma up in a vacuum bag as she dies, explaining that a mother will die after raising her son. The boy then disposes of her body in the hole, seals it up, and leaves Yonder with the couple's car, refilling it with gas he acquired from an unknown source, possibly through the hub. He arrives at Prospect Properties, and finds an elderly Martin awaiting him. Martin hands over his name tag and dies. The boy, now taking on the name of Martin, seals his predecessor in a vacuum bag and then literally folds him up, disposing of him through a filing cabinet. Assuming Martin's post, he waits until a new Human couple enters, and rises to welcome them and give the sales pitch, repeating the cycle.

Appearances

 * Vivarium (2019)