Suddenly, your body began to sink into the water. Katie noticed this and suddenly jumped off you shouting, "Oh no, did I pop it?!" She took you in her arms and started feeling around your body for the valve, an act you enjoyed despite the dread that, maybe you were popped. Finding none, she got an idea; she pushed you entirely underwater; if you did have a leak, surely she would see bubbles.
it was strangely easier since you seemed to be getting heavier. Indeed, you felt that your inside was filling up and your rubbery skin was becoming flesh again. Suddenly, you gasped; filling your lungs with water. Katie saw this and jumped back until she hit the far end of the pool.
You look yourself over to find you've become a real version of the mermaid pool toy you once were. Seductive curves; sleek, glistening, emerald green tail and long, luxurious hair were your new traits. New thoughts buzzed in your head, about the mermaids, yourself and Katie. Suddenly, you realized, you were underwater. You launch yourself straight up out of the pool, and spray the water in your lungs from your mouth like a water gun.
"Holy shit!" Katie shouted, having not taken her eyes off you since your change. "A real mermaid!"
She was clearly afraid, but at the same time, excited about you. After pondering many things, you decide to swim over to her and introduce yourself.
"My name is Jessie and I need your help." You say to her.
"Sure, what do you need?"