The only species that is absolutely a native species to Brighthaven.
Their primary enviroment are swamps and other wetlands. Sometimes they can be found near lakes or slow moving rivers, but this is rarer. They are usually crepuscular to nocturnal but can be active any time of day. Their diet is omnivorous as adults and carnivorous as children. Their primary grain is rice but they mostly turn it into a type of beer rather than eat it. Eating isn't something they need to do every day, and unless they are children or gestating eggs, generally only eat every few days. They are also able to stop eating for up to 2 months without prep or up to 4 if they've stored enough fat on their body. They do however need water daily.
The lifespan is roughly 2-3 centuries and they are capable of reproducing after 30 years or when they get close to their adult sized. They are capable of reproducing every year but most only do so every few years. Females lay roughly 10 eggs which are guarded carefully. Young hatch after 90 days and are tiny so they stay in a nursery pond that is cared for by the entire family. Despite this usually only one in ten of each hatchling lives during this time. This part ends when they turn 10 at which point they start talking and spending most of their time on land. They are also named and considered a full member of the family.
They are cold blooded as children but as they become adults they are able to do some thermoregulating (although not to the level of true warm blooded creatures). They prefer temperatures in the 80s to 90s but adults and larger kids can handle even freezing temperatures for a few weeks (although they will fast during this time). Young children will die below mid-70s and, in areas where this is a concern, the nurseries have either heating elements or natural hot springs to keep the area warm enough for them.
They are a 3'5" to 4'3" tall, mostly bipetal (they can walk on all fours but it's more awkward the taller they are) lizard, body is long proportional to their legs. Four fingers on hand (including one opposable thumb) and four webbed toes on their feet. Finally, they have a crest that starts just above their eyes and goes down their back to their tail where it turns into a tail fin for swimming. This crest is taller in sexually mature males
Children under ten mottled brown green and gray including crest, eyes are always a dark brown.
Once they turn ten the mottling goes away and they turn into a solid brown lizard. Their eyes change into their adult colors at this time as well.
Adult coloration for females is brown with a green crest and their eyes are almost always green. For males their body color is dark greens with bright blue spots on the back and with a yellow, orange, or red crest and their eyes almost always match their crest.
Serosep hatched with bright gold eyes are called Sun-touched and keep this color for their entire lives.
The colors that indicate sexual maturity start showing up around their late 20s but isn't fully developed until they're 30 for females. Males just continue to get brighter and their crests redder with every shed until well after their first century and half.
Clothing
When among their own kind they don't wear clothing, unless they need to for cold. If among other races that are weird about nudity they tend to prefer loose robes. If their a part of a group with clothing requirements they follow those.
They do wear rings pierced through their crest at various parts. These are made of metal or polished wood or bone and indicate family group, rank and other important information. The first ring is set when they reach ten.
Herbalism & Healing
They are the best healers on Brighthaven. With that said they usually cannot heal directly, instead they are able to make potions and enchant them to be much better at healing than they normally would be. The few who can heal directly, called the Sun-Touched are the only ones allowed to wear gold crest rings and are treasured by everyone. Sun-touched are also able to anti-heal, which can weaken or even kill. This magic is only allowed during self defense and hasn't been seen since the Mage Wars.
They are also masters of local herbs, fungi, and other forage, with the best knowing every plant and fungus in their environment and what use, if any, it has.
Immunity
They are immune to any illness that is found among other species and they are also immune to any poison or venom native to Brighthaven. Their immunity to illness allows them to work as healers during even the most virulent plague safely. Illness they can catch are few and all of them are easily healed by their potions.
Crafts
As Seroseps primarily work in wood they are masters of it. Their houses, small boats, furniture, and other house gear are almost all made of wood. These are all often elaborately carved and dyed with natural dyes in bright reds, oranges, and yellows. They are also great basket weavers and potters. They do work some with stone, and prefer to avoid metal as much as possible (no taboo... it's just impractical in the wetlands). When they do use metal it's mostly brass, although after stainless steel was invented they will sometimes use that instead.
They tend to live in extended families that are lead by the elders. Serosep tend to identify themselves to outsiders by the name of their family, which is an animal or plant that is also viewed as a protective spirit by that family. Neither gender leaves the family and, since incest isn't a taboo, they will breed within a family group. With that said, they are aware too much can cause issues in the blood line, so some years families will send their males out to find mates in other families. Any child born of such union is a member of the mother's family.
Culturally speaking; they are pretty conservative but also have a very strong "live and let live" way of thinking when it comes to other peoples, as long as those peoples leave them alone in return. With that said they do consider most other species to be colonists and, with a few exceptions, have a polite but cold relationship with them. They consider Daughters of the Stars to be fellow natives, and the two groups get along very well. Of the colonists they get along best with Moonrunners (who all fought on their side), Unicorns (who stayed out of the fighting and healed both sides equally), and Merfolk (who only got involved when they were drug into it). They also get along ok with the Vesla, mostly because the Vesla made it abundantly clear they would have been on their side during the war had they been there.
They are animists who's primary gods are the Sun and the Earth (genders depend on who's asking). Their rituals are very much seasonal and locality dependent. If they live near others with different religions they may also incorporate their religious beliefs into their religion, as long as there's no conflict. Also the Serosep religion is mostly open and most peoples on Brighthaven practice some elements of it, such as reciting certain prayers when dealing with Brighthaven's waterways. Also there is no priesthood or shaman or anything like that. The Elders of each family, however, are the ones who teach their ways to the young. They do have a body of mythology and folktales but no central book. Also these myths do change depending on the family group, although those who live close to each other tend to have similar stories and rituals.
Regarding death, for the most part, they believe as the body rots into the ground, their memories and knowledge are gathered by the family's guardian spirit and kept by them. Any named member of the family (named members are anyone who was given a name during the naming ritual at the age of ten or so, and can include adopted children) may then tap into this body of knowledge via special rituals that each family keep secret. These memories are mostly accessed when they run across something no one living has dealt with or to settle an argument.