"Allow me." The blue/black haired mermaid, who is Sapphire, pulls herself away from the tide, straightens up, and gestures for both and Rachel to come closer to the rocks. You do so, and kneel - and the mermaid places a hand each on the forehead of you and your mate. "You will see last night through my eyes," the mermaid announces softly.
A vision appears in your mind's eye. You recognise the beach where you are now, but it's bathed in the light of the practically-full moon, at night. Next, you see Deirdre and Felicia walking, enchanted, towards the singing mermaids. Witnessing the seduction of the young women from Sapphire's point-of-view, you watch as Felicia is caressed at the water's edge, before being encouraged to drink two offered vials of sparkling liquid. Then Felicia removes her clothes and wades into the sea with Sapphire. The Spaniard gasps as she experiences a sudden, last period - then her form changes. Her breasts flatten, and her genitals push outwards - before she discovers her legs joining together to form a flexible, scaly tail, complete with a caudal fin and membrane.
Meanwhile, in the vision, a naked Deirdre screams upon feeling her neck developing gills. She breaks away from Emerald, and runs onto the beach. At the edge of the cliff, she collapses and witnesses her legs fuse into her new fishtail.
"Sapphire!" the green-haired mermaid yells. "This one has only drank of the vials! She is still female. We cannot reach her!"
"Deirdre!" Sapphire cries, in response. "You belong with us, now! Crawl back to the sea, and be with your friend!"
Next, you hear laughter coming from the cliff. Sapphire's memories continue to unfold in your mind, as a party of satyrs climb down to the beach, grab the newborn mermaid, and carry her off like a sack of potatoes...
Deirdre's screams fade as Sapphire removes her hands from and Rachel - and you are returned to the present time. "That is truly what happened," the head mermaid declares. "We could not help her. I am sorry."
Rachel sucks in her breath. "No! Are those...fiends...so base, they have to resort to kidnapping...anyone...now, for their pleasure?"
"And in the first place, what gave you the right to transform our friends against their will?" you ask sternly.
Emerald inclines her attractive face towards you. "Our ways may be strange to you, I accept - but your friends were feted to join us. And our school needs new mermen, for us to survive."
You rise up and stomp your fore-hoof on the rocks. "Except that Deirdre's in danger, now! What will happen to her? Surely those beasts can't turn her into a satyr?"
"I believe their master, Cedius, is aiming to use your friend to gain access to the Labyrinth, and seize the Eyes of Zeus and Hecate," Sapphire answers thoughtfully. "If he finds both, he will obtain the power of a god, and be able to transform almost anyone on the island into satyrs, under his control! Even those who were human and are already changed into other forms will not be immune!"
You take a deep breath. "Even us centaurs?"
Sapphire's grim expression turns more serious. "I said he would be able to transform 'almost anyone'. You pair are creatures now dependent on two hearts. If you are changed back into single-heart bipeds, the shock to your bodies will kill you!"