Name: Selther
Age: Unknown
Likes: relaxing in the warm water, seeing the floor of the ocean the few times she goes there, carefully watching humans, her fish friends
Dislikes: winter, cold water, the hooks of fishing rods, when she's uncovered, when she's out of water.
Other: she's a salt water lake mermaid

Name: Thrash
Age: Unknown
What he likes and doesn't is unknown to most aquatic life, the ones that know refuse to speak.
Mermaids and mermen love the aquatic animals, but they need to eat too as well as some of the vegetation, so he throws his trusty spear at dying, seriously injured or very dangerous fish.
He's an ocean merman

Scenario: make it up