The Mermaid stands over the bed, knife in hand. She prepares to finish her work and put an end to the Prince that spurned her. Before she can, she hears a soft voice in the darkness. "Wait."
It is the Girl. She is in the doorway in nothing but a thin nightgown, candle in her hand casting a warm glow over her face even as her trembling hand causes the shadows to dance like specters.
She enters cautiously, as if the Mermaid would spook and run away. She would not. Even still the Girl is gentle as she sets down the candle and takes the Mermaid's hand in hers. If she is surprised at the cool, scaly texture, the slight brine of seawater that lingers, she does not show it. Her face is kind and scared and soft. The Mermaid might pity her, if not for the emotion in her eyes that the Mermaid does not yet know how to describe.
"He's talked about you, you know. The mysterious woman who saved him on the beach that day. I used to think he loved you, more than he loved even me.
"But I was wrong. He loves nothing in this world but himself and his money. I have seen how he treats his servants, how he has treated me from the minute we were married."
Slowly, tenderly, she eases the knife from the Mermaid's hand.
"He deserves to die, yes. But first he deserves to suffer. Help me with this."
The Girl places the knife gently on the bed and returns to the doorway. The Mermaid finds that she cannot help but follow, the Girl's golden hair as entangling as seaweed around her ankle. In the hallway a rabbit waits in a wooden box. Its nose twitches and it beats its legs in panic as the Girl lifts it and brings it to the bed. Its fur is soft and dry as the Mermaid holds it, and the Girl retrieves the knife.
The Prince sleeps soundly as the Girl and the Mermaid slaughter the rabbit and cover the room, the sheets, and the Prince's hands in blood and chunks of gore. They take the bones and pelt and leave the castle, laughing.
In the morning, the Prince is seized for the murder of his beautiful young bride.
In the morning, the Girl and the Mermaid wake to the shimmering of the sunrise on the waves, their bodies tangled and bloodstained clothing long discarded.
No guards have followed their trail, but as the sun emerges fully over the horizon to witness their deeds, they know their time here has run out.
The Mermaid's pain dissolves with her borrowed flesh as the seafoam reclaims her. The Girl watches quietly, unable to offer any comfort save the single tear that slides from her face to join the expanse of the ocean. She is alone, but her peace is hard-earned.
Legends tell of the maid on the shore, wandering the sand in bare feet, clear voice ringing out in mournful song. Legends tell of the fate of the men who have tried to claim her.
Some say she roams the coastlines still, calling to her lost loves, receiving only the murmur of crashing waves as her response.