The skin on Ava's legs began to take on a color and texture like black latex. Now she remembered the costume. After starting with a traditional mermaid tail, the photoshoot people had suggested a non-traditional mermaid. Ava had never heard of a cecaelia but she had seen "Little Mermaid" as a kid and remembered Ursula. The black latex outfit had eight tentacles - like an octopus - around her waist and she had been posed so her real legs were hidden. Ava felt the slick skin of her new legs and loved the sensation, but soon her legs felt very strange. Her whole body tensed then shuddered. Her legs spasmed uncontrollably until each tore apart into four tentacles.
Ava at first struggled to control the tentacles, her brain used to two straight limbs instead of eight flexible ones. She managed to get into a sitting position and examined herself. The black latex skin continued to spread upwards from her waist, giving her a perfect flat stomach. As it reached her breasts they perked up and soon she had perfect C-cups that would make a supermodel jealous. The latex kept going, up to her collarbone, but no higher. Then down her arms to her fingertips. She caressed her transformed upper body, marveling at how fantastic she looked. Examining her lower boy she found her buttcheeks were gone, replaced by the upper part of two of her tentacles. She still had a crack between them. Her vagina was still right between her two front tentacles.
She was a sexy beast. And a horny one. She concentrated on what she needed and a tentacle bent back to rub her slit. Then she slid slowly in, her own tentacle a perfect fit for herself. But she didn't want to have all the fun by herself. She directed another tentacle under the sheets to wrap around Ethan's cock. Ava began to masturbate herself and Ethan simultaneously with her new tentacles, thinking gleefully of the month ahead...