Cassandra thought about it for a moment. All the while, Alexis continued to caress Cassandra's legs with her tail.
"Yes, I want to become a mermaid. Does it require magic?"
"Sort of" said Alexis. "You should take off your pants; they'll just get torn up when you transform."
Cassandra stood up to remove her overalls then had second thoughts. Getting naked in front of a stranger made her a little uncomfortable. Alexis sensed her hesitation.
"I can look away if it would make you more comfortable" she said.
Pushing off from the shore, Alexis swam slowly across the oasis. Cassandra quickly unstrapped her overalls and slid them to the ground, along with her panties. That left her only with her pink t-shirt and the sports bra underneath. She waded into the oasis until the water was up to her chest.
"Now what?"
Alexis turned back to her, swimming in a slow broad circle around Cassandra as she spoke.
"You mentioned your father. What about your mother?"
"She died when I was very young."
"That's what your father told you?"
"Yes. He raised me on his own."
"Your father, a fisherman, lived on the ocean. He never tried to disuade you from the idea that mermaids were real. You were always drawn to the ocean, always wanted to meet one, often pretended to be one. I bet you could hold your breath a really long time too."
"Yeah, so?"
"How do you think you sailed into this magical realm?"
"I don't know. You said humans from my world can't enter yours on their own. I guess someone left a magic portal open? Or there was weak spot in the border between worlds?"
"Or you're not from your world. At least not entirely."
"I'm from Gaia?!" exclaimed Cassandra.
"Not quite. You probably weren't born here, but your mermaid mother was."
"If I was half-mermaid wouldn't I know it? Wouldn't I have transformed already or something?"
"Not neccesarily, especially growing up in a non-magical world. But you can definitely transform here in Gaia."
"Something to release my inner mermaid?"
"Something like that." Alexis swam face to face with Cassandra. "You're going to have to trust me. And remember: breathe."
"What?"
With no further warning, Alexis grabbed Cassandra's arms and pulled her underwater. Cassandra instinctively struggled, but the mermaid had a firm grip. Then she remembered what Alexis had said. Against all sense, she opened her mouth and took a deep submerged breath.
The water filling her lungs choked her for a moment. Then the next thing Cassandra knew she was breathing water. And if she could breath underwater... Cassandra closed her eyes and pressed her legs tightly together. She thought of mermaids and her days swimming in the ocean mermaid-style. She felt something touch her legs and quickly realized it was Alexis' mermaid tail. She felt that odd yet pleasant sensation again, the one she'd felt earlier when Alexis had caressed her Cassandra's tail with her legs. But it felt a little different now - still smooth but like...scales against scales.
Cassandra opened her eyes and saw Alexis smiling at her. Looking down, instead of her legs she now found a scaly pink mermaid tail. Cassandra bent her tail in a way human legs couldn't move, to prove to herself once and for all it was real.
Cassandra kicked with her new tail toward the surface and took a deep breath of air. Alexis surfaced in front of her a moment later.
"I'm a mermaid!" exclaimed Cassandra.
"You're a beautiful mermaid!" agreed Alexis.