Sirsk
The Sirsk is an invasive, parasitic species, that have since grown to create an entire civilization; and has even been deemed a risk by a goddess - no easy feat.
Location
The Sirsk live in a separate plane, known as the plane of Sonomia. This plane houses those that Riias, the goddess of protection, deem to be a danger to the "true world". Many people who find themselves in Sonomia did not cross by choice, but instead crossed by mere mistake; by getting lost or by following malicious directions by a spirit. It is difficult to return to the true world once you enter Sonomia, as you need to ask someone who is capable of transporting themselves and you back. Likely, you'll need to catch the eyes of Riias, or another deity that is traveling through Sonomia, and prove that you have not been damned to remain within.
The "Cruel" Goddess
Riias, the goddess of protection, had noticed the species and kept them on close observation; hoping that the spores would not be able to organize themselves. after realizing her err (and almost causing a world-altering calamity), Riias quickly isolated each infected person into a village, and with a snap, sent them to Sonomia.
Riias does care for the village, though tends not to show her true self within, for fear of retribution - starting a witch hunt is not in her cards; fixing the mistake of not providing water, and allowing for the Sirsk to have a plot of forest for lumber to be obtained. Another god had since noticed the plight of the Sirsk and has been subtly trying to win over their favor, by opening rifts for the unfortunate to wander through; and using their own spirits and demons to send people to the village through false rituals and misdirection.
Culture
The Sirsk village is calm during peacetime, when there is nothing going on. Trapped in a past where electricity had not yet been discovered; where gas was the main power - they mainly use rickshaws for transport, if they are carrying large quantities of items; otherwise foot-travel is permitted, and the community is built to be walkable.
Sirsks are civilized, though quick to excite. Their daily lives are similar to those of the "new-world" as they put it; though they use bartering instead of currency, and have since set a standard on how much things "cost". The vast majority do their own labor, and provide for themselves, using a plot of community-maintained land to farm, while the officials of the village are provided for with donations.
Religion
A Sirsk may inform you they are non-religious, but an in-depth look reveals they are united on one religious standpoint, their deep hatred for the Goddess that entrapped them within their village; forbidden from entering the tree line.
An Odd Diet
The Sirsk are, as stated before, alien; and did bring alien vegetation along with them to sate their hosts. The fruits are easy to cultivate and are mainly grown due to their unique flavors, quick maturity, and versatility; they can be cooked to their base flavors: sweet, spicy, sour, bitter among the flavor options. Among one of the fruits is "Kurzget" (lit. Fruit of Power), a fruit that has a remarkable similarity to an energy drink. The vegetables are hearty.
Dialect
The Sirsk will use their own language when creating names for a person, place, or thing, though prefer to speak in common for regular dialogue; since they wish to use it to "impress" tourists.
Infection Mechanism - A.K.A "Tourist Hospitality"
Once a person of another species visit, They may find themselves inundated by many Sirsk. The outsider will be treated like royalty, always being kept close to one of the villagers while they are being taken to lavish dinners, shown experiences and plays. The Sirsk will be careful not to allow the trails to be seen by their visitor, permitting the visitor to watch the trails of performers, nothing more. The visitor may even find a companion or couple looking to house them on the condition of sharing the bed. The visitor will never be left aloe, and will be explicitly steered away from leaving the village.
Criminal Punishment
If a Sirsk are accused of committing a crime, then they will hold a vote within the village. transgressors, criminals, and other nigher-do-wells will be trapped within the confines of a tiny cell that barely contains them, and a tube will be strapped to their mouth. Anything they displace from their body; be it spore, hair, or anything else, will be vacuumed from the space and used in the gas lines that power the homes in the village. The tube will be used for nutritional intake, torture, and to collect spores. The criminal will be held until they die from atrophy.
Appearance
Commonly, you will find tropical and exotic hair & fur colors; pink, green, blue among the list of potential colors, potentially mixed or fading into each other. Otherwise, the Sirsk closely resemble a fox, cat, or dog demihuman; the species mainly depending on the predecessor infecting them.
Trails
One unique feature a Sirsk has is the ability to make a colored cloud of spores, known by the community as a "trail". These clouds are used to measure how agitated (or excited) someone may be; and are the same color (if not a mix) as the fluff.
Infection
it is commonly (mis)understood (even by the Sirsk themselves) that the breath of a diseased, or a carrier, is the main mechanism for the spores, when it is in fact the ears and tail shaking that release spores; the mouth being the point of transmission for carriers. Constant exposure to the spores is required in order to progress through the stages of infection.
Infection progression
Once a person is infected, they will find themselves to have an itchy throat, increased fluid intake, reduced fluid output, as the spores attempt to breach the airway. Coughing and complaints of irritation are common complaints. anti-fungal treatments and fresh air is suggested to get rid of the infection at this stage.
As the airway has been breached, the spores will attempt to take in the spinal cord, beginning to build a network of roots around it. Spasms, sudden loss of feeling, dizziness, sudden temporary paralysis, and phantom pains are common. Oxygen therapy and anti-fungal treatments may work in the early stages, but as there is enough rooting, surgery may be required.
Once the spores have taken full root, and have wrapped around the entire spinal cord, they will begin to instruct the infected person's body to make the spleen into a breeding ground for more spores to be asexually created and released into the bloodstream. By this point, the infected must undergo invasive surgery to remove the affected organs and remove the roots surrounding the spinal cord is necessary, along with oxygen therapy, and anti-fungal treatments (inhalation and injection).
At this point, the infected is past the point of return, and saving their life becomes impossible. If the infected did not die of infection, then they will die of trauma, as the roots penetrate the heart, lungs, and force protrusions both into the spinal cord, and out of the head/tail area. The heart and lungs will be forcibly pumped to maintain blood circulation. If there are ears present, then the body is instructed to destroy them. Tails present will be rooted into, and turned into a place to spawn. The brain will be quickly overtaken by the roots, and will be cut off and repurposed as another area to reproduce.
Rarely, the Sirsk may search and retain memories and feelings, known by the community as a "consciousness transfer", and a sign of "bonding" as it were, with the idea being that the Sirsk taking control of the person "loved" the host to the point they would have the host continue to be in control. This is a fallacy, however, as the Sirsk is using the previous memories, and adopting the same pseudo-personality of the host to continue their life, then develop their own memories, since the host themselves are dead.