*crashes through door, breathless* TELL ME ABOUT THE MERMAIDS
Haha, YES, I am introducing mermaids into the Curse-Verse!
Mermaids are very much mer-invested, they rarely interact with humans. They have their own problems and don't feel like bothering to get involved with another species' issues. There are different tribes depending on where you live: Northern tribes, tropical tribes, etc. Typically the tribes stay separate and deal with their own territories. Honor is a Big Deal for them, so any outliers who break the laws are punished swiftly by the tribal leaders. If the rogue mermaid flees into another tribe's territory, the tribe first sends an emissary to inform the other tribe's leader, who will either hunt the rogue themselves or allow the rogue's people to take care of it.
The mermaids can take human form, if they want, but they have to get permission from their tribal leader/elders, and they have to have a REALLY good reason for doing so. If they transform WITHOUT the permission, they are basically considered dead and any return to the tribe will be met with a swift execution. They have a basic knowledge of humans and society, so when they DO go ashore they're easily able to blend in.
As humans, they appear mostly normal aside from being abnormally fast, strong, and observant. In their natural form, they have thick, muscular tails, scales all up their torso/chest/shoulders, a dorsal fin on their back, claws on their webbed hands, and two rows of sharp teeth.
This is all I've got so far! Thanks for the ask!