Merfolk

Overview

Mermaids. You might have heard about Sirens, but be aware that a Mermaid might looks like a Siren to a degree, but is something totally different. They are lovely most of the time and - if they can understand your language - are a good chatpartner. Most of them want to know more about us surface-dwellers, because we are good tradepartners and storytellers. There are stories about Merfolks drowning people or pulling them out of curiosity or love under water, but those are just that: stories.
Lets dive deeper into the topic of Merpeople.
From "Life under Water - Mermaids and other sentient beings"

What is a Mermaid? Well, they are the distant cousin of the Sirens and, in contrary to the Sirens, friendlier to surface-dwellers and nasty against the Sirens and the Masters. Like the Sirens they have a female and a male side and both cousins hate each other. They hate each other so much that they kill each other where ever they go... uhm... swim. Float?
Why do they hate each other? Because Merfolks are friendly to surface-dwellers and want nothing from them except stories and a little bit of trade, whereas Sirens eat surface-dwellers and are more often slaves to the Masters; sometimes on their own free will, sometimes bound with corrupting magic. And since their family leaders had sworn to protect the surface world against the Masters, the occasinally slaughter is never far away.

"Care to purchase anything?"
"What do you have in mind?"
"Your... pipe against this amber?"
"You can smoke under water?"
"No, they are just pretty."
"Okay then..."

— Human trader with a Merman

Under the Sea...

As Sirens the Merfolk can breathe under water. This is made possible with a set of two systems: Lungs to breathe over water and a set of four gills at the position where humans have their sixth and seventh rib. On a female body they normally sit right under their breasts while males have them in the open and so they have to protect them at all costs. Merfolks can survive without gills or lungs, but then can't breathe under or over water. One system can't replace the other system. One less gill or lung is not a huge problem, but more can be dangerous.
Merfolks are fierce warriors. They use weapons like tridents or spears made from stone, wood or corals and are friends with octopods, dolphins and all kind of jellyfish and normal fish.. They don't hesitate to attack and kill Sirens when they can, but are more tactical with it since Merfolks are not as many as the Sirens.
As Sirens the Merfolks live in coral houses and caves and whatever ruins or places they can find. A family can grow up to around twohundred of Merfolks before they splinter up in smaller families to find spouses.

Reproduction

This part is relatively easy. They reproduce through sex. It looks like two fish laying on top of each other, but thats it. The Merman enters the body of the Mermaid with his... well, penis, and injects his semen. Both reproductive organs are roughly at the same spot as with humans right above the beginning of their fish tail. The Mermaid grows a child inside their belly for seven months and give birth to a child.
Labour can happen on land or under water, whatever the Mermaid feels like or deems safer. Most of them give birth under water so their child can use their gills right from the beginning. It is way easier to teach breathing with lungs then teach them the way of gills.
The first four to eight months the Mermaid feeds their child with their breasts like surface-dwellers. At this point one might think about how the Merfolk came into existence. Has someone seen a fish and was like "I'd tap that!"?
Well, no. The Eternal Death created the Masters for shits and giggles, but the Eternal Life wanted to have a counterbalance and created the Sirens. But they sided with the Masters - at least a few of them - and so she grabbed a human and some fish and slapped them together in the next attempt for the counterbalance to the Sirens and the Masters. And it worked. This is the reason the Merfolks looks a lot like humans mixed with fish.
Just like Siren they have stronger muscles and bones than surface-dwellers to counter the pressure under water. So a swing from a Siren/Merfolk is deadly as hell, even deadlier than a Garladans lightmagic.

What do they eat?

That part is easy: they are on a pescetarian diet. They eat fish, clamps, octopods, shark, eel, seaweed, some not so crunchy corals, sponges...

Armoury

To get rid of the Masters (as the ultimate goal) and defend themselves against the Sirens, the Merfolk use a lot of corals and carefully crafted iron compounds for tridents, daggers and armours which protects their fins, gills, lungs and heads. Some combine metal with fishblades and use them as off-hand. Some might spot an elvish sword or a dwarven battle axe in their hands, but those are exceptions from sunken ships.

Appearence

Male Merfolk

An armed Merman by CrazyEddie via Midjourney

An armed Merman by CrazyEddie via Midjourney

An armed Merman by CrazyEddie via Midjourney

Female Merfolk

An armed Mermaid by CrazyEddie via Midjourney

An armed Mermaid by CrazyEddie via Midjourney

An armed Mermaid by CrazyEddie via Midjourney