Raindeer!!!

ok leaving the haterism bit to answer this genuinely

honestly this applies to any au, not just mermaids, but I’d much rather read something where the writer considers WHAT the universe-altering aspect REPRESENTS and what it replaces. did the original world already have magic, and can it be substituted by mermaids (and does it work with the whole world and not just the bits related to the ship you’re writing this au for)? if not, did the original world have a narrative where characters are separated by factors beyond their control? was there a character with a canon arc that could translate well to being/becoming a mermaid? I feel like this is often ignored in favor of just retelling the little mermaid, but this time the characters look like and are named after other characters.

oftentimes, aus fail to interest me because they change the backstories to such an extreme degree that the characters couldn’t possibly be the same people anymore. for example, there’s no real way to do a modern no-magic coffee shop au of avatar the last airbender that doesn’t remove most of the stakes of what makes aang—a kid thrust into a war with the responsibility to save the entire world at the age of twelve, who feels responsible for the demise of his entire civilization and culture—interesting!! if you take all that away from him, then why does the character in question need to be aang if you could replace him with, like, peter parker and get the same outcome.

ALL THIS TO SAY!! you can do whatever you want. There’s no right or wrong way to participate in fandom. personally, I like engaging with fandom by playing with the material given and doing character/narrative analysis, and some people don’t!!