Thomas' Adventures of The Little Mermaid

Thomas and Twilight Sparkle's Adventures of The Little Mermaid is a Thomas/MLPFIM/Disney Crossover film creating by 76859Thomas.

Plot
Ariel, a sixteen-year-old mermaid princess, is dissatisfied with life under the sea and curious about the human world. With her best fish friend Flonuder, Ariel collects human artifacts and goes to the surface of the ocean to visit Scuttle the seagull (who is an old friend of Salty), who offers very inaccurate knowledge of human culture. On this particular day, Ariel meets Thomas, Twilight and their friends (and now along with Salty) who have been sailing around the ocean for quite some time and they all decide to stay with her for a while. Ariel ignores the warnings of her father King Triton and his adviser Sebastian that contact between merpeople and humans is forbidden, longing to join the human world and become a human herself.

One night, Ariel, Flounder, Thomas, Twilight, Salty, the others and an unwilling Sebastian travel to the ocean surface to watch a celebration for the birthday of Prince Eric on a ship, with whom Ariel falls in love. In the ensuing storm, the ship is destroyed and Ariel saves the unconscious Eric from drowning. Ariel sings to him, but quickly leaves as soon as he regains consciousness to avoid being discovered. Fascinated by the memory of her voice, Eric vows to find who saved and sung to him, and Ariel vows to find a way to join him and his world. In the meantime, Sebastian, Flounder, Thomas, Twilight, Salty and the gang vow to keep this a secret so no one will know what happened. Noticing a change in Ariel's behavior, Triton questions Sebastian about her behavior and learns of her love for Eric. In frustration, Triton confronts Ariel in her grotto, where she and Flounder store human artifacts, and destroys most of the objects with his trident. After  Triton, instantly regretting his actions, leaves, a pair of eels, Flotsam and Jetsam, convince her to visit Ursula the sea witch in order to be with Eric. Suspicious about their plans, Thomas, Twilight, Salty and the others, along with Sebastian and Flounder, follow them to find out what their up to.

 Ursula makes a deal with Ariel to transform her into a human for three days in exchange for Ariel's voice, which Ursula puts in a nautilus shell. Within these three days, Ariel must receive the "kiss of true love" from Eric; otherwise, she will transform back into a mermaid and belong to Ursula. Ariel is then given human legs and taken to the surface by Flounder, Sebastian, Thomas, Twilight, Salty and the others. Eric finds Ariel, Thomas, Twilight, Salty and the others on the beach and takes them to his castle, unaware that Ariel had saved his life earlier, assuming her to be a mute shipwreck survivor and Thomas, Twilight, Salty and the others are her friends and they are shipwreck survivors, too. Thomas, Twilight, Salty and the others  tried to tell Eric that Ariel here was the one who saved his life before, but he does not beileve them. At the end of the second day, Ariel and Eric almost kiss but are thwarted by Flotsam and Jetsam. Angered at their narrow escape, Ursula disguises herself as a beautiful young woman named Vanessa and appears onshore singing with Ariel's voice. Eric recognizes the song and, in her disguise, Ursula casts a hypnotic enchantment on Eric to make him forget about Ariel.

The next day, Ariel and our heroes find out that Eric will be married to the disguised Ursula. Ariel cries and is left behind when the wedding barge departs (Thomas, Twilight, Salty and the others feel sorry for failing her again and Twilight sadly sings the song "I've Got to Find a Way [from Magical Mystery Cure]" as the rest of our heroes are looknig sad and ashamed). Scuttle discovers that Vanessa is actually Ursula in disguise, and informs Ariel who immediately goes after the wedding barge. Sebastian informs Triton, and Scuttle disrupts the wedding with the help of various animals. In the chaos, the nautilus shell around Ursula's neck is broken, restoring Ariel's voice and breaking Ursula's enchantment over Eric. Realizing that Ariel had saved his life and Thomas, Twilight, Salty and the others are telling the truth, Eric rushes to kiss her, but the sun sets and Ariel transforms back into a mermaid. Ursula reveals herself and kidnaps Ariel. Our heroes went after them. Triton confronts Ursula and demands Ariel's release, but the deal is inviolable. At Ursula's urging, the king agrees to take Ariel's place as Ursula's prisoner. Ariel is released as Triton transforms into a polyp and loses his authority over Atlantica. Ursula declares herself the new ruler and a struggle ensues in which Ursula accidentally kills Flotsam and Jetsam. In her rage, Ursula uses the trident to grow into monstrous proportions.

Ariel and Eric reunite on the surface just before Ursula grows past and towers the two. She then gains full control of the entire ocean, creating a storm with a maelstrom and shipwrecks, one of which Eric commandeers. Just as Ursula attempts to destroy a trapped Ariel in the maelstrom, Eric runs Ursula through the abdomen with the ship's splintered bowspirt, killing her. Ursula's power breaks, causing Triton and all the other polyps in Ursula's garden to revert back into their original forms. Realizing that Ariel truly loves Eric, Triton willingly changes her from a mermaid into a human. Ariel and Eric marry on a ship and depart (with Thomas, Twilight, Salty and the others happily watching).

Trivia

 * Salty is guest starring in this film and is revealed to be an old friend of Scuttle.
 * Thomas, Twilight Sparkle, the whole gang and Salty are able to breathe underwater due to Twilight's magic making them impervious to drowning.
 * Flashback is used from Thomas and Twilight Sparkle meets Peter Pan.
 * In the song "Kiss the Girl", Thomas, Twilight, the whole gang and even Salty are all shown to be singing the song with Sebastian.
 * This film takes place after YakkoWarnerMovies101's film Pooh's and Ash's Adventures of Scooby-Doo: Halloween Hassle at Dracula's Castle (which the steam team already know Ursula the Sea Witch).