The Little Mermaid

Ariel trades her voice with Ursula because she wants legs to walk on land and be with Prince Eric, whom she saved from drowning. Ursula offers her the deal in exchange for her voice, giving her three days to get Eric to kiss her. If she fails, Ariel becomes Ursula's prisoner forever. This desperate choice reflects Ariel's deep longing to experience the human world and be with Eric.

Earlier, Ariel expresses her desire to be "Part of Your World" and watches Eric's birthday celebration, showing her intense attraction to the human realm.

If Ariel fails to receive Eric's kiss within three days, she becomes Ursula's prisoner forever. The contract states that she will belong to Ursula and be trapped in the sea witch's lair. This deadline creates urgent tension throughout the film as Ariel must quickly earn Eric's love while unable to speak and reveal her true identity.

King Triton destroys Ariel's collection of human artifacts in a fit of rage after learning about her feelings for Eric and her fascination with humans. Sebastian tells Triton about Ariel's love for the human prince, which triggers Triton's strong disapproval of humans. In his anger, Triton uses his trident to destroy her cherished items, including the fork she found at the shipwreck, causing a major rift between father and daughter.

Triton's disdain for humans is established earlier when he confronts Ariel about her fascination with the human world and forbids her from exploring above the waves.

Vanessa is actually Ursula in disguise, using Ariel's stolen voice to manipulate Eric. After taking Ariel's voice, Ursula transforms herself into a human woman named Vanessa and schemes to marry Eric herself. She uses Ariel's voice to charm Eric during the carriage ride and boat ride, making him believe she is the woman who saved him. This deception allows Ursula to steal Eric's potential kiss that would have broken her spell.

Flotsam and Jetsam interrupt the romantic boat ride, suggesting Ursula is actively working to prevent Ariel from succeeding.

Ariel recovers her voice by shattering the enchanted shell necklace that contains her voice during the engagement ceremony. When Ursula transforms into her monstrous form, Ariel fights back and breaks the magical locket that holds her voice, releasing it back to her. This happens just as the three-day deadline approaches, freeing Ariel from Ursula's complete control and allowing her to speak again.

Scuttle infiltrates Vanessa's chambers earlier and discovers the enchanted shell, giving Ariel the opportunity to retrieve it.

Triton gives his trident to Ursula during the final battle to protect Ariel from her. When Ursula reveals her monstrous form and drags Ariel underwater, Triton confronts her. In a moment of desperation to save his daughter, Triton surrenders his trident, granting Ursula extraordinary magical power. This sacrifice puts Triton in a vulnerable position, though it ultimately allows Eric and Ariel to work together to defeat the sea witch.

After defeating Ursula, King Triton transforms Ariel back into a human using his magic. Touched by Ariel's bravery and her love for Eric, Triton grants his blessing and uses his trident to reverse the transformation, giving Ariel human legs permanently. This allows her to be with Eric on land and marks the beginning of their life together.

Triton's transformation magic is established when he initially grants Ariel legs through his deal with Ursula.

Eric enters Ursula's lair to rescue Ariel after seeing her being dragged underwater by the monstrous Ursula. Despite being on land, Eric dives into the ocean to confront the sea witch, showing his love and commitment to Ariel. He fights Ursula alongside Ariel, eventually using an abandoned ship to defeat her when Ariel spears the witch with the vessel's jagged edge.

Eric had previously declared he would find the mysterious girl who saved him, demonstrating his determination to be with her.

Ursula wants to overthrow King Triton because she is his older sister who was banished from the underwater kingdom. She harbors resentment toward Triton for taking her place as the heir to the throne. By capturing Ariel and eventually gaining Triton's trident, Ursula plans to seize control of the underwater kingdom and rule as queen, fulfilling her long-held ambition for power and revenge against her brother.

Ariel rescues Eric during the storm because she happens to be nearby when his ship is destroyed by the violent weather. She sees him falling into the ocean and dives in to save him from drowning, bringing him safely to shore. This act of bravery is what makes Eric determined to find the mysterious girl who saved his life, setting up the central romance of the story.

Earlier, Ariel watches Eric's birthday celebration from the shadows, showing her attraction to him before they officially meet.