The whole concept of her transformation is pretty scary. Her body is not her own anymore. She has to adapt to a new form that is painful and unnatural. And the fact that she has no real guarantee of a happy ending, that she could just disappear into sea foam, gives the story a sense of dread and horror.
The isolation that the Little Mermaid experiences is quite horrifying. She is alone in a human world, unable to fully communicate. Also, the threat of death if she fails to win the prince's love is a constant, terrifying presence. It's not a typical fairy - tale scenario when you look at these aspects closely.
The deal with the sea witch is a major horror element. She has to give up her most precious possession, her voice, and endure the transformation into a half - human form that causes her constant pain. It's like a Faustian bargain in a way.
The idea of the Little Mermaid losing her voice can be seen as a horror element. She gives up such an important part of herself for a chance at love with the prince. Also, the sea witch's deal is quite terrifying. She has to endure great pain when getting her legs, like feeling as if she's walking on knives. And in some darker interpretations, the possibility of the prince never loving her back and her turning into sea foam is a tragic and somewhat horror - like end.
One element could be a dark twist on the sea witch. Instead of just taking her voice, the witch could turn her into a grotesque half - fish, half - monster. Another element is the prince's betrayal. He could use the mermaid's love for him to his advantage and then abandon her in a cruel way. Also, the ocean itself could become a source of horror, like it turns into a blood - red color and is filled with mutated sea creatures that attack the mermaid.
In 'The Little Mermaid' horror might be found in the mermaid's isolation. She leaves her family and everything she knows behind. In the human world, she's alone and vulnerable. There are so many unknowns for her. And the fact that her fate hinges on the love of a man she barely knows is really quite scary. If he doesn't choose her, she faces a very bleak end. It's not the typical happy fairy - tale situation, but rather has elements that can be considered quite horrifying.
In the real little mermaid story, one key element is the mermaid's longing for a different world. She is not content with her underwater life and dreams of the human world above. Another element is the sacrifice she is willing to make. She gives up her beautiful voice in order to have a chance at getting legs and experiencing human life. Also, the pain she endures, both physical and emotional, is an important part. For example, every step she takes on land is like walking on knives, but she still perseveres in her pursuit of love and a new life.
Once upon a time, the little mermaid made a deal with the sea witch. But instead of a beautiful transformation, she was cursed. Her voice became a shrill screech that drove all sea creatures mad. Her new legs were made of jagged bones that cut into the sand as she walked. And every step she took was in agony. She was shunned by humans, and in the end, she was dragged back into the ocean by the vengeful sea witch to live a tortured existence in the darkest depths.
One dark element is the mermaid's sacrifice. She gives up her voice to the sea witch, which is a huge loss. Also, she endures great pain as she tries to walk on land with every step feeling like knives. And the idea of her potentially losing her soul if the prince doesn't choose her is quite dark.
The powers of the mermaid can make a story scary. For instance, if a mermaid can control the sea, create huge waves, or sink ships at will, it's terrifying. A mermaid that uses mind - control on humans through its song is also a great element. Moreover, a backstory of the mermaid being cursed or having a vendetta against humans can add depth and horror. Say, a mermaid who was wronged by humans in the past and now seeks revenge on all seafarers.
The Little Mermaid could be regarded as a horror story because of the deal she makes with the sea witch. The witch takes her voice in exchange for legs. Imagine being mute in a strange world, not being able to communicate your thoughts or feelings. Also, the idea of walking on knives (how the legs feel to her) is a very cruel and horror - like aspect of the story. And there's always the threat of failure and losing her life that looms over her throughout the story.
To retell it as a horror story, you could start with the mermaid's growing obsession with the prince. Show how it drives her to madness. Then, when she's in the human world, make it seem like everyone is out to get her. The prince could be more of a cold and cruel character, and the mermaid's hope slowly turns into despair as she realizes she may never truly be loved by him. Add some spooky events like strange noises at night and shadows following her.
You could start by making the sea witch more evil. Instead of just taking the mermaid's voice, she could take away her memories or her ability to swim properly. The prince could be a cruel character who toys with the mermaid's feelings. And when the mermaid starts to turn into sea foam, it could be a much more violent and painful process, with her body contorting in agony.