In a fanfiction, Serena as a mermaid might be part of a mermaid kingdom that has a long - standing feud with a group of sea - dwelling Pokemon. Serena, being kind - hearted, tries to bridge the gap between the two sides. She uses her charm and the skills she has learned in the Pokemon world to negotiate peace, all while looking stunning with her mermaid tail and long flowing hair.
One possible plot could be that a Pokemon, like Vaporeon which has a mermaid - like appearance, gets transported to the world of The Little Mermaid. It befriends Ariel and helps her in her quest to understand the human world. Vaporeon could use its water - based powers to protect Ariel from Ursula's evil plans.
I think Misty from the Pokemon world could be a main character in this fanfiction. Since she has a connection with water - type Pokemon, she could easily fit into the underwater world of The Little Mermaid. Along with her, a Psyduck would be there. Psyduck's clumsy yet powerful abilities could add an interesting element to the story. And of course, Ariel would be a main character. She could learn a lot from Misty about the Pokemon world and they could team up to protect both their worlds from any threats.
The plot might start with Serena finding a strange, enchanted shell on the beach. When she touches it, she is turned into a mermaid. In this new form, she realizes she can communicate with water - type Pokemon in a different way. She embarks on a journey to find the origin of the shell and the power that transformed her. Along the journey, she makes new friends among the mermaids and Pokemon, and together they face a powerful villain who wants to use the shell's power to take over both the sea and the land.
To write such a fanfic, you need to understand the characteristics of both the Pokemon and The Little Mermaid. For the Pokemon part, know their abilities, personalities, and how they usually behave. In terms of The Little Mermaid, be familiar with the story's themes like love, adventure, and the relationship between the mermaids and other sea creatures. Start by creating a scenario where a Pokemon enters the Little Mermaid's world. Maybe it's through a magical portal. Then, build the story around how this Pokemon changes or affects the world and the characters there. You can also add some conflict, like a Pokemon being hunted by an underwater villain who wants to use its powers for evil.
Ursula as a mermaid in fanfiction might also explore her backstory more deeply. She could have been a mermaid princess in a far - off part of the ocean. But due to a power struggle or a curse, she lost her status and became the villain we know. This could add a lot of depth to her character and make the fanfiction really engaging.
One possible plot could be that a Pokemon, like Vaporeon which has a mermaid - like appearance, gets transported to the underwater world of The Little Mermaid. It could make friends with Ariel and help her in her adventures. For example, Vaporeon could use its water - based powers to protect Ariel from Ursula's evil spells. Maybe it could also communicate with the sea creatures in a unique Pokemon way, which would be fascinating for Ariel and the others.
Love and relationships are also quite common. Whether it's her relationship with Ash in a new light because of her mermaid form, or new friendships she forms with other water - type Pokemon. In some fanfictions, there's a theme of acceptance. Serena has to deal with how others will accept her as a mermaid, especially those who are close to her like her friends and family in the Pokemon world.
One way to find good Pokemon Serena Mermaid fanfiction is to search for it on Tumblr. There are often communities dedicated to sharing and discussing such fan works. A lot of these fanfictions might incorporate elements of Serena's journey in the Pokemon series, like her contests, but with the added twist of her being a mermaid. It could be really interesting to see how her mermaid abilities interact with her Pokemon skills.