oml im so so sorry for not getting back to you earlier!! Completely forgot to log in here.
Basically Hydrolls are a completely user friendly species, if you want to make your own lore, feel free to do so, if you want your hydroll to be part of another universe or story, again feel free to do so :3

I will be working on expanding the toyhouse world soon so you can see every info and lore we have for them. But again besides a few redesign rules were quite open to everything!
Ill be more active on here again so if you have any questions feel free to ask here or Chanacabra