"If you wish to become a merman, Neil, you will need to make love to me." Topaz smirks at you, looking you up and down.
You feel taken aback. For a long moment you say nothing, then you manage to find your voice again.
"Er... I'm flattered by your offer... But we've only just met! Um...is there another way? One that allows a temporary change of form, perhaps?"
Topaz narrows her brow, in disbelief. "You are actually turning me down?"
"No offence, Topaz. But not all men are as easy as you seem to think! Let's be friends. I need you to trust both me and Caroline."
The mermaid sighs. "I will trust you. I was not being very truthful, with my offer. It is just that I have not had the pleasure of choosing a male for...close companionship...since my capture, at sea. And yes, I think I can provide a non-binding transformation for you."
You hear the doorbell ring. Excusing yourself from the sexually-frustrated Topaz, you rush to the hallway and let Caroline in. Thanking her for coming, you quickly lead your old friend back to the bathroom.
"Wow!" Caroline runs her hands through her shoulder-length, ginger-brown hair, as she stares at Topaz with her wide green eyes. Getting the mermaid's permission to touch her, Caroline examines the other female's waist - and satisfies herself that no costume trickery is involved. "You really are the genuine article!"
"Thank you, Caroline." Topaz twitches impatiently. "Now will you two stop gawping, and take me to this swimming pool you have in mind? Or better still, can you please return me to the sea?"
Caroline looks at you, then at Topaz. "Well, I guess we should... But I'd like to know more about the people who captured you! For all we know, they might end up knocking on our doors, looking for a missing mermaid. Was there anyone - or anything - else being kept at that mansion?"
"I didn't check out the other rooms," you confess.
"To my knowledge, I was the only captive," Topaz replies. "And if you fear that the doctor and her associates will punish you for helping me - that is easily remedied. Come with me! I can transform you both into merfolk! You will love my world."
Caroline looks gobsmacked - then she turns to you, to gauge your reaction.
"She's told me this, already," you admit. "Our guest here wants us to help the survival of her race - by joining it."
"You're kidding, right?" Caroline challenges the mermaid.
"I am serious. I have some magical ability, and can cast a spell on either, or both, of you - so that when immersed in water, you humans can become like me." Topaz smiles. "But if you prefer, you will revert back, when dry again! However, this option means your bodies can only transform to merfolk form and back three times. After that, the spell will be spent."
"Now that sounds like a better plan," you mutter thoughtfully.
"A better plan than what?" Caroline raises an eyebrow at you.
"Er... Never mind." You turn a shade pink. "Let's talk about this downstairs, shall we?"
She nods, and you both head to the kitchen, to talk the situation over some tea/coffee and biscuits.