Mary watched as parts of her legs turned a shade of gray like a dolphin's tail. The color spread until everything below her waist had turned gray, from the tips of her toes up to just above her hips and below her navel.
She thought this was perhaps the extent of the changes. She ran her hand down her stomach and onto her leg. It was a smooth transition from her normal skin to skin like a dolphin's in touch as well as look. She noticed her lower body was now completely hairless - also like a dolphin - and her toenails had disappeared.
Mary wondered what if it would feel any different to swim like this. She took a step toward the pool and nearly tripped. She looked down to find her toes merging together and her foot flattening. She decieded she had better sit down instead and stepped toward a nearby chair on the pool deck, but had trouble moving her legs. Mary tried to find the cause and quickly realized her legs were slowly drawing together, working down from her crotch. She awkwardly shuffled toward the pool chair, finally flopping into it as the merging of her legs passed her knees.
Mary tried to pull her legs apart, but she could not. The change continued pulled them together all the way down to what had been her heels. Her feet were completely flattened out into dolphin flukes. Now stuck together, her legs merged into one appendage - an unmistakble dolphin tail. She ran her hands down the sides of her tail, amazed to be dolphin below the waist and human above. She noticed her slit remained, but of course now being like a dolphin's.
Laying in the pool chair, Mary considered what to do next. She could slide out of the chair and drag herself a short distance across the pool deck to the vials, either completeing the change into a dolphin or trying something else. Then again, being a dolphin-mermaid might even be better than a full dolphin and the pool looked terribly inviting. What to do?