Jessie Walker hauled herself out of the pool and tried to catch her breath as the national anthems of the winners filled her ears and the medals were handed out. That was it, all those months of training and years of dreaming crewed up and thrown out the window and all because she had a cramp in her leg at that very moment when it counted the most. She pulled off her swimming cap and shook the water out of her close cropped black hair whilst rubbing the spasming muscles of her thigh and trying not to think what she would do in the face of her resounding defeat.
Far away, atop Olympus, Zeus tried to keep a straight face as his brother oggled the mortal swimmer sitting on the side of the pool. He had to admit that she was eye-catching, athletic figure, deep brown eyes and younger than the over-sexed deity by a good few millenia.
"As lord of the oceans," Poseidon began, stroking his beard, "I claim the right to mete out this disgraced mortal's punishment."
All eyes fell upon Zeus, who nodded without saying a word.
"In the element that thou hast failed," Poseidon roared, "forever whilst thou be a creature." And with that he brandished his trident at the floating image of Jessie.
Suddenly, the muscles under Jessie's hands began to spasm again and again. She felt the bones under her skin shifting and she heard the fabric of her bathingsuit strain and finally tear as her legs merged before her eyes to form a tail, silver and studded with scales. All eyes in the crowd were suddenly drawn to her and gasps filled the air as Jessie the mermaid prodded her tail with a hand she now noticed was webbed. She took a deep breath and was shocked to feel three gilslits open on either side of her chest just below the arms.
Jessie pulled her tail up beneath herself and desperatly pulled the remains of her costume down, confused and terrified at what she had become.