Julie looked expectantly at Miley, waiting for her to do something to change her back. Miley just smiled and swam in front of her.
"Are you sure you want to go back there, being a mermaid is so much better than your boring human life." Miley said as she floated right in front of Julie. Julie considered it, while she loved her tail, and had a lot of fun playing with Miley in the sea, she wasn't going to just leave her family like that.
"Sorry Miley, I need to get back to my family, but we can do this again tommorow right?" Julie asked her. Miley just smiled and moved forwards, now right in front of her. She put her hand on Julie's shoulder, caressing her.
Julie felt really weird, this was kinda odd.
"Hey Miley what are you doin... Mnnph!!" Julie was cut off as Miley grabbed the back of her head and kissed her, her tounge snaking inside her shocked mouth, as she kissed her. To stunned to do anything, she floated there, as Miley tounge darted in and out of her mouth, giving her pleasure she had never felt.
"Miley what the hell are you doing!!" She gasped when they pulled apart for air. Miley just smiled seductivly, as she wrapped her tail around Julie as the floated together, on hand stroking her back as the other held her chin.
"Convincing you of the worth of being a mermaid with me, forever, and if not you, then defiantly your body." She said as her hand removed Julie's top, letting her breasts hang free, nipples perky. Julie was stunned, only able to watch as Miley then removed her own top, leaving them both topless. "After all, isn't this wonderful!" Miley said as she buried her face in Julie's tits, suckling on her nipples and squeezing them in turn. Moaning in pleasure, Julie could only grab Miley's shoulders, and hold, unable to stop her. She shuddered with pleasure, nigh overwhelmed.
She then felt Miley kiss her stomach, then down, kissing her belly until she reached the start of her tail, having unwinded her tail from her, though julie could not move to escape. She reached her mermaid cunt, wet noticeably underwater. Julie whimpered "Miley please stop this, this isomer what I wanted, please no."
Miley smiled and said "You may not wish this, but your body wants it badly, and once you orgasm as a mermaid, you can never go back!"
And with that Miley descended on Julie's pussy, lapping and licking it, driving julie to the brink. Her tail twitched in pleasure, and she couldn't stop moaning. Miley stopped licking her pussy, and put her finger in it, once again intertwine their tails, she rose to face Julie, whose terrified face was torn in pleasure and terror.
She kissed Julie again, fingering her with one finger. She knew Julie couldn't last much longer. Julie felt her hand cup her breast, and felt the waves of pleasure as Miley put two more fingers into her. She wanted to run, to cry but this felt so good. Her family, her legs, her humanity, she could feel it slipping away with each thrust. Mewling she was brought to the edge of climax.
"Cum with me Sister!!" Screamed Miley as she trusted harder. Julie screamed, arching her back and shacking as she climaxed, a wave of pleasure so great it was impossible. She floated there, shocked as she felt deep within her change, forever a mermaid. Miley hugged her, breasts mashing against each other as she kissed the new sister. "Welcome home, Sister" she said to the sobbing Julie.