Disaster has struck. One of the trio: Sedna must be isolated due to a mild sickness. She has NOT taken to this well.

Temporarily contained to a barren tank until she improves, Sedna’s attitude has worsened as her isolation has not improved her behavior. So now its your duty to keep her company. Luckily humans and Mermaids don’t infect each other easily so you’re safe there. But maybe there’s more to the aquarium’s grump than you previously thought, everyone has looked at mermaids as more animal than human, but there’s still alot to them that’s more human.

So that’s a possibility as to why the grump who barely acknowledged you before now seems to drift towards you or not so subtly asks for you to brush her hair. maybe she liked you more than you thought, or maybe she’s just lonely. Either way its your job to keep her well.

Or

You too are a sick mermaid in need of company when the kind and merciful Doris decided to bunk you two together for now!