Sharing my OC lore(ish) bc why not ^^
The parasite travels from plankton to smaller fish, but causes no major changes or harm to the animal. Their true target are the bigger fish, such as barracudas, sharks and pike. After being ingested once more, the parasite starts to develop inside the predator. The fish will start to have a bigger appetite, as some of its nutrients are for the unknown parasite growing inside of them. The parasite starts off looking like a human fetus, and as it grows it starts to eat away at the fish's stomach. The parasite will continue to eat as it grows, making the majority of the food the fish eats go to them, leaving only enough to keep the fish alive. As time goes on, the parasite starts to focus more on the fishβs brain. The parasite does not go against the fishβs natural instincts, as it is similar and that is the reason these types of fish are picked. The fish gains a more βhumanβ consciousness, making them more aware of their surroundings, giving them better hunting techniques, etc because the parasite knows the fish will die soon so there is no reason to try and fight with its last moments. As the parasite gets older, it will push its way out through the fishβs mouth, creating the tail merfolk have. As the parasite grows, its body merges with the now dead fish, the only purpose it serves being a tail and transportation for the siren. The parasite also merges its new body with the dead fish, making sure it doesnβt decay as the parasite has no legs. The siren is now fully conscious, able to make its own decision and recognize things similar to humans, but with the same instincts as the predatory animal it originated from. It is also able to travel to farther parts of the ocean that the fish from before may have drowned in.
Similar to the βsirenβ parasite, the parasite also travels from plankton to the fish, however this is when the changes start. The βmermaidβ parasite focuses more on the appearance of the fish, unlike the βsirenβ parasite who focuses on what fish can fulfill its needs regardless of looks. Because of this, the Parasite has to contort and mutilate the fishβs body even more, serving as painful to the parasite as well. Oftentimes the fish are too small to handle the parasite as its full size, leaving mermaids with scars that are covered by the clothing and jewelry they steal. Their development is the same as the βsirenβ parasite, but the process is more slow and painful for the fish and parasite. The parasite also struggles to make rational decisions, relying on the fish and keeping it alive longer than it should. When the parasite fully develops, it has more disadvantages than advantages. While pretty on the outside, the βmermaidβ struggles with swimming large distances, digestion, swimming, etc. After almost going extinct, they found themselves able to lure in prey using hypnosis through singing. As time went on, many sea animals developed an immunity to this hypnosis, and so they started to hunt humans instead. This is where the term βsirensβ came from, but some confusion caused them to believe that sirens were the ones that developed from the parasite βsirensβ and mermaids were just pretty sea folk. This causes issues between βsirensβ and βmermaidsβ, because sirens were being hunted for no reason while mermaids got to be praised by humans even though they are the true perpetrators. Both species have something against each other even though they technically are the same species, as the mermaid virus is just a mutated version of the βSirenβ parasite. .
A species equally hated by humans, βsirensβ and βmermaidsβ. ??? develop the same as sirens, except they are βmore beautifulβ like mermaids. They have the mermaids ability to sing and use hypnosis on people, as well as having the same hunting skills and smarts as sirens do. What really makes them disliked is the fact that they have legs. As they develop inside the fish, they are able to grow legs and eventually separate themselves from the fish they came from. This gives them the ability to walk on land, and as long as their legs are covered they can almost fully pass as humans. They are very rare though, and often die early on. The reason they are called ugly is because sirens think that because of their legs and similar appearance to mermaids they are better than regular sirens. Mermaids are jealous of the fact that they do not suffer the same pain they did in order to have their appearance, and humans hate them because they just hate everything thatβs different.
Sirens: Sharp teeth and claws for hunting, skin and body the same color/texture of the fish they developed from, curly hair, jaws that open fully in order to make eating easier, eyes the same as appearance the fish but with better eyesight, more toned/muscular bodies due to hunting, gills on sides of their stomachs, larger ears,, sometimes wear stolen jewelry for fun
Mermaids: Teeth similar in size to humans but sharper, webbed hands, more βhumanβ skin tones with colorful scales of the fish they came from, longer and straight/wavy hair, often covered in jewelry and fabrics to cover the scars from their development and upper body if female, regular jaws, small fin ears, no sharp nails, βhumanβ eyes dilated pupils, very strong vocal chords
???: Human skin colors with the colors of the fish they originated from covering their legs and sometimes arms, long nails, retractable teeth to make longer, jaw that fully opens, human-like eyes with black sclera, can have any hairtype, large fin ears, instincts of the fish they came from, also wears jewelry and clothing for fun, strong vocal chords
Siren: 20-500 years (depends on what kind of fish they came from)
Sirens: Survival of the fittest. They donβt act violent on selfish desires or petty feelings, but only in self defense. They can have families and friends, and they tend to keep to themselves for the sake of their safety. They have no government and instead follow their own morals aside from agreed upon ideas (Donβt kill for no reason, mind your business, etc.)
Mermaids: Faker than fake. They pretend to care about each other's well being, but in reality they know itβs everyone for themselves. They have a queen who they entrust with full power as she is their βmotherβ (The first mermaid) and feel whatever she claims is just and true. They are taught that sirens are savages and that humans are who they should aim to be like. They all see themselves as one big family under their queen.
???: They live completely by their own accord. Some try to blend in and live as humans, others wander between the water and land, avoiding all creatures as much as possible. Tend to develop their own morals and opinions based on their environment, but at the end of the day will always do what they want even if itβs the opposite of what theyβre told.
This was made a while ago so I apologize for any grammar mistakes, but I shared part of this in a discord server and decided to put it all here
