sorry, I'm still trying to figure it out. The reader has, well, some specific (adopted?)parent, why are others after her? For example Tyrest or DJD, Overlord,Deathsarus
My rules have a very basic timeline if that helps.
This is a merformers a.u where Reader is a half mer who was adopted by a human Ratchet at a young age. They grew up on land unaware of their abilities until they realized they could breath underwater. Once they learned about this ability they began meeting new mers!
Pharma is their real father and a mer in this a.u Hes apart of the DJD pod and Tarns mate. Tarn can't have children and steals the egg sacs (like tcoggs) of other mers trying to have kids. Pharma who typically does this surgery eventually explains he has a child but they are on land and are only half mer and he lost them long ago. Tarn gets the amazing idea of stealing this child and raising them with Pharma (Even though they are full grown)
Reader being half mer has some very special abilities and powers. They later find out about these skills and influential mers like Tyrest want them because they believe their a descendant of Primus.
Those are some of the basics. I hope that helps :)