About the story of the boy who turns into a mermaid. He isnt a permanent mermaid only when the tide is high or at night. The moon does play some small role though. I originally had him have a phobia of water. I wanted him to be a bit of an outcast. Scrawny, effeminate, afraid of water. Does the fear of water take away from him having a hard time with the transformation?
No. Use it against him.
Make it painful for him to be away from the water. He can’t breathe. It burns. whatever.
But, mentally it hurts him to be in it. Give him that internalized struggle. Pin his mind against his body.