"I wish you were human again," I said.
We waited.
Nothing happened.
"This isn't funny," Amanda said. She was feeling her scales with one hand while trying to hide her bare breasts with the other arm. Out of consideration, I looked away, though she was still distracting.
"I wish Amanda had legs again," I rephrased. Maybe the ring counted mermaid as a kind of human already. Nothing again.
The thought that the ring had stopped working turned my spine to ice. "I wish we were our normal sizes again!" I yelled, becoming a little frantic.
After a moment's disorientation I was full size, looking down at the aquarium turned pool. A tiny mermaid Amanda was still there, and it looked like she was yelling. I was still nervous about the ring, but chivalry demanded I join her. I wished again.
"--back here!" she finished yelling as I returned to the pool. She quieted down when she saw me. "Don't leave me like that, please. Now what's going on? And can I at least have some clothes?"
I wished a blouse onto her top. Of course, she was still naked from the waist down, but that didn't matter as much. Or at least, it was a symptom of a larger problem.
"I guess the ring affects me, but not you. But why?" I wondered.
"I wish we knew..." suggested Amanda.
Right. "I wish we knew why the ring doesn't affect you." Suddenly, it was so obvious, I couldn't believe I'd missed it. The ring was originally crafted by merfolk. They sometimes gave them as gifts, but didn't want anyone using it to affect them, so they added the limitation that it would never alter a mermaid. There was no exception for humans who had recently turned into mermaids.
There was one way around this, I realized just as quickly. Amanda, who must have been following the same line of thought, said it first. "No one can change a mermaid with it, but a mermaid can change herself. Give it to me!"
There was no help for it. And besides, with all the trust she'd given me, I could hardly say no. "I wish I could remove the ring," I said, remembering my first wish. Then I took it off and handed it to Amanda.
She slipped it on and immediately shouted, "I wish I were human again!" Her tail quickly split from the bottom and shaped into two legs, and her scales all fell out and faded away on the ground. The bikini top and bottom even reappeared. She gasped in relief. "Thank you."
"Can I have the ring back now?" I asked.
"Oh, soon enough. But you did give me quite a scare. I think you owe me at least a few wishes first. For one, I wish..."