A sea witch could also be the main villain. She might be jealous of the Little Mermaid's new friendship with Peter Pan. So, she casts dark spells on both of them, causing chaos in Neverland and the underwater world. For example, she could make the mermaids in the lagoon forget how to swim and make the Lost Boys lose their way in Neverland.
Captain Hook could be the main villain. He might see the Little Mermaid as a new target or a way to get to Peter Pan. He could try to capture her and use her as bait to lure Peter Pan into a trap.
Maybe a new character, a dark fairy who is envious of the magic in both Neverland and the underwater kingdom. This fairy could try to steal the magic from both places. She would be a powerful villain as she has the ability to manipulate both land and water elements, and she sets out to destroy the friendship between Peter Pan and the Little Mermaid.
Captain Hook would be an obvious choice as the main villain. He already has a long - standing feud with Peter Pan in the original story. In a Kingdom Hearts fanfiction, he could team up with the Heartless or be influenced by the Darkness to become even more menacing. He could also be after the power of the Keyblade, thinking it would give him an edge over Peter and his friends.
One idea could be that Peter Pan takes the Little Mermaid on a flight over Neverland. She gets to see all the magical places from above, like the Lost Boys' hideout and the mermaid lagoon from a whole new perspective. This could lead to a friendship where they exchange stories of their different worlds.
The Mermaid Lagoon in a Peter Pan fanfiction can be a place full of mystery and magic. Imagine a lemon - colored flower that only grows there. Peter Pan is intrigued by it and the mermaids warn him not to touch it as it has powerful magic. But Peter, being curious, touches it anyway. This leads to a series of events where he starts to see illusions and has to rely on the mermaids to break the spell, creating a story full of adventure and the unique charm of the lagoon.
Ursula is an obvious choice as she is the main villain in the original Little Mermaid story. In a Kingdom Hearts fanfiction, she could be even more powerful, perhaps having made a deal with the Heartless or some other dark force to gain more control over the underwater world and other worlds connected to it.
Maybe a new character, a powerful sea witch who has been influenced by the power - hungry ways of some of Naruto's villains. She wants to rule both the underwater world and the land world above. She would use her magic to create chaos and try to stop Naruto and Ariel from uniting their forces.
A merman who was once in love with Ariel but turned bitter when she chose Eric. He could team up with some sea monsters and try to take Ariel back to the sea against her will, believing that she made the wrong choice in leaving the ocean for a human.
A group of mermaids from a far - off and isolated reef who are jealous of Ariel's family and their influence. They could plot to make Melody look bad in front of the underwater kingdom.
It could be a group of outcast Lost Boys who have turned bad. They might be jealous of Wendy's special place in Peter's heart and in the group. So they kidnap her in an attempt to show Peter that they are in control now and can disrupt the harmony of the group.
Captain Hook would initially feel victorious. But then he might realize that Peter was an important part of Neverland's balance. Without Peter, the eternal battle that gave his life purpose is gone. He could start to feel lost and even a bit regretful for all the times he tried to kill Peter.
In a Peter Pan fanfiction centered around the Mermaid Lagoon, lemons could be the key to a hidden mystery. Suppose there is an ancient prophecy in the lagoon that mentions lemons. Peter Pan hears about this from a mermaid and decides to investigate. As he delves deeper, he finds that the lemons are related to an old magic that once protected the lagoon. But over time, the knowledge of this magic has been lost. Peter Pan then teams up with the mermaids to rediscover the power of the lemons and use it to protect the lagoon from a new threat, perhaps a dark force that is slowly encroaching on the beautiful and magical place.