Sirenia
Sirens are an aquatic race that dwell within the sea, though often explore on the surface world. While their appearance varies depending on the particular sub-species, common identifiers are their webbed hands, guills, and sharp teeth.
All siren are born with a 'water spirit'. They're viewed as their own personal guardian angel, and the Sirenian takes on personal and physical traits of the animal they match. Although they can sometimes manifest representations of their spirit via their magic, communication is purely done emotionally rather then through words. It is very similar to how cosmic magi have stars and can bond with them.
As for physical traits, all Sirenia have fragile sharp teeth that are serrated. It is not uncommon for teeth to break and grow back again within a few weeks. Molars do not develop until a Sirenian enters their mid-teens, and do not grow back like the rest of their teeth if broken. A Sirenian may choose to either cut raw meat into strips or unhinge their jaws to open their throat space to swallow it whole until then in order to work around their inability to chew. They need a heavy meat diet to survive, and things such as to many vegetables or desserts can make them ill. Although their 'human' forms are all very similar, it can be easy to tell the difference as each subspecies has subtle cues.
Sirenian blood is green and thick. It has a more coppery taste to it then regular blood. Recovery rate is higher for the Sirenia, healing a quarter to a third quicker than humans. However injuries from fire and other magics they are weak to have double the recovery rate. Their skin color ranges from pale grey, to greenish yellow, to blue, to very dark. Although quite varied in color, it always has a hint of unnaturalness to those who normally live on land.
Species
Mermaid
Children of Galene.
The most common of the Sirenia. They take on aspects of any type of fish, such as sharks, flying fish, tuna, that sort of thing. Mermaids are often the most social of the species, choosing to live off of coastal cities. They have translucent skin that has a greenish quality to it. Gills along either side of the neck, and ears are either pointed or in the shape of fins. Either or both fingers and toes are webbed. Their hair often has strange but bright coloration as well, which matches the color of their tails.
Anguill
Children of Scylla.
Sirenia that usually live in the deep sea. Their aspects are varied between eels, sea snakes, and in rarer cases, sea slugs. Their tails are long and flexible rather then finned. Their eyes are sometimes a little fair apart, and their skin seems clammy, a little sticky and somewhat moist. They also have very thin lips but wide mouths, with their ears are often smaller and more rounded than a humans. They also have longer and broader noses then most as well.
Selkie
Children of Leucothea.
Nearly all Selkie live inland, in rivers and mainly the swamp. Their creatures are of aquatic mammal nature, seals, otters, walruses, manatee. Sea Selkie often have traits of orcas or dolphins, and are the rarest of all Sirenia. They're the only Sirenia who cannot breathe underwater. Their nails are colored black or a dark hue and very thick, with fur around the fingers, hands, and feet. Eye coloration tends to be pitch black, and their eyes have a glassy tone to them. Busy eyebrows and beards are also common. Those with whale spirits do not have any fur or hairy traits at all, but are prone to having annoying laughs.
Society
Water Spirit
As stated previously, the water spirit is an entity that is born and dies with the Sirenia. It is similar to a summon spirit, however it has its own mana circuitry. They often choose to be invisible, or show themselves using magics that the Sirenia is familiar with. Such as a Mermaid's spirit might be made of water, or a Selkie's made of dark magic.
The animal that is born with a Sirenia is not related to anything other then species. However the type of spirit you have can greatly affect your place in society. Those with more powerful animals like sharks are expected to take positions in the military, and those with more intelligent such as octopus are expected to be scholars. Smaller animal spirits are considered to be useless, it is not uncommon for parents to abandon children who might be weak as a result of their spirit affinity.
Water spirits play a vital roll in the coming of age ceremony for Sirenia. The Sirenian sings for their spirit and asks them for more strength. In serious cases, they may choose to attempt to strengthen their relationship further by binding their mana circuits together. However this can be a dangerous process and requires a channeling stone to help focus the spirit's energies.
Spirits are practically invulnerable to all magics except those that directly harm the soul. Using such magic to destroy the spirit will kill the Sirenian as well.
Names
Although any Sirenian may choose to have a last name, it is not a part of their family structure. Thus any last names tend to be over the top and extravagant, not always passed on to any children they choose to have.
Instead, a name of a child is traditionally a mesh of the two parent names. Example, Zaniyah being a construct of Zabor and Galniyah. Those whose parents do not wish to pass their names on often have single or double syllable names, like Rise.