A possible plot could revolve around the baby's special abilities. Since Lady Rainicorn has her own set of abilities, it's likely the baby will inherit some. In the fanfiction, the characters could be speculating about what those abilities might be. And as the pregnancy progresses, there could be some signs or events that give hints about the baby's future powers. This could lead to a lot of anticipation and excitement among the characters.
A cool plot could be that Jake and Lady Rainicorn discover a hidden dimension. In this dimension, they find out that there are versions of themselves with different powers. They have to work together to find a way back home while also learning from these alternate versions. Or perhaps a story where they are invited to a royal ball in the Candy Kingdom but end up getting caught in a mystery involving a missing jewel. They then use their unique skills to solve the mystery.
Another possible theme is the exploration of different cultures within the Adventure Time universe. Lady Rainicorn comes from a different species, and fanfictions can delve into how her culture and Finn's human - like culture interact and influence each other.
One interesting fanfiction could be about Finn and Lady Rainicorn going on a magical quest together. They might encounter strange creatures and have to use their unique skills to overcome obstacles. Finn's bravery and Lady Rainicorn's flying ability would be really useful in such a story.
Finn would probably be very protective. He might stand guard outside her resting place and keep a lookout for any potential danger. Jake, on the other hand, could use his shape - shifting abilities to make things more comfortable for Lady Rainicorn, like creating soft beds or warm blankets. Princess Bubblegum might use her scientific knowledge to make sure Lady Rainicorn has a healthy diet and proper medical care.
One way is to show them sharing their secrets. Lady Rainicorn could tell Jake about her family in the Rainicorn Kingdom and Jake could share his dreams for the future. They could also have arguments over small things like what to have for dinner, which shows their closeness and comfort in being honest with each other. Then, they make up and their bond becomes stronger. Also, they can protect each other from danger. When Jake is in trouble, Lady Rainicorn uses her horn's powers to save him and vice versa.
One plot idea could be the mystery around how Arceus became pregnant. Since it's a very powerful and almost god - like Pokémon, it could involve some sort of divine intervention or a very special event in the Pokémon world. Maybe other Pokémon are in awe or even a bit afraid of what this could mean for the balance of the world.
Perhaps the story could focus on how their friends from the neighborhood react to the news. Some might be excited and offer help, while others could be jealous or worried about how it will change the dynamics of the community. For example, Jock might be overly protective and constantly check on Lady, while Peg could offer fashion advice for when the puppies are born.
The fanfiction could also be about the challenges Chloe faces during her pregnancy. For example, she might have health problems during the pregnancy. She could also face social issues, like dealing with people who judge her for being pregnant at a certain age or in a certain situation. The story could show how she overcomes these difficulties and grows as a person.
One plot idea could be that Natsu has to deal with the physical and emotional changes of pregnancy while still trying to be part of his usual adventures. Maybe his friends are super protective of him now.
One idea could be focusing on how her friends and family react to the news. They might be surprised, excited, or worried. For example, her best friend could offer to throw a baby shower. Another idea is exploring how Naruko prepares for the baby, like setting up the nursery or choosing baby names.