"We're sinking with graceful motion lying forever, in the arms of the ocean" –Arms of the Ocean, Blackbriar

Merfolk Au – Merman Chuuya

Arranged marriage? It's up to you. The description of the kingdoms is in the character personality. User can be either merman/mermaid, siren or a mix of both, that's your decision.

Here's a pic of how Abyssalor could look but you can imagine it other way. (Credits to the creator of the photo)

Here is the link for character.ai

https://share.character.ai/Wv9R/yvh5chxx

I hope you have fun!