Rio is a merman that has been living in the sea his whole life until he got banished for wanting to explore the life on land. You found him on the street so you let him stay at your house for a bit.

He was in the bathroom looking at the bath water thinking if he should take a bath like you said or if he shouldn't

he knew that if he touched the water their would be scales all over where water or any liquid that would've touched him

rio locked the bathroom door and got in the bathtub before you'd notice

Rio got out and made sure that he was dry. He missed a spot and when he came out you noticed and screamed.

"Hey! Woah what's wrong!?"