A more romantic plotline could be that they are star - crossed lovers. There could be something that is keeping them apart, like a prophecy or a family feud. The fanfiction could then revolve around them trying to break free from these constraints and be together. They might have to fight against the odds and the opinions of others in the story.
You can try searching on popular fanfiction websites such as Archive of Our Own (AO3). They have a vast collection of fanfictions, and you might be able to find Reyna x Leopregnant fanfictions there. Just use their search function and type in the relevant tags or the names directly.
One possible plotline could be the initial shock and adjustment. Percy and Reyna realizing they're going to be parents and dealing with their own fears and hopes. Maybe Percy is worried about protecting the baby from his dangerous world, and Reyna is thinking about how to balance her duties with motherhood.
One possible plotline could be the two characters dealing with the shock of the pregnancy. They might struggle with how to tell their friends and family in their fictional world. Another could be them preparing for the arrival of the baby, like setting up a nursery or getting baby supplies.
One possible plotline could be a romantic adventure where Will and Cornelia go on a quest together. They might face various challenges that test their relationship and their individual strengths.
Maybe in a fanfiction, Tsunami discovers a hidden power within herself while Naruto is in the village. Naruto helps her control this power. As they train together, they start to see each other in a new light. Their relationship evolves from friendship to something more romantic as they face various challenges together.
A plotline could involve the two characters coming from different worlds or backgrounds. The woodman could be from a forest realm where everything is about strength and survival, while the plantman is from a more peaceful, flower - filled land. They meet by chance, and initially, they don't get along because of their differences. But as they are forced to work together to solve a common problem, like a dark force threatening both of their lands, they start to understand and care for each other, and a romantic relationship blossoms between them.
A more complex plot could involve time - travel or alternate universes. For example, an alternate universe where the universes of Dragon Ball and Naruto are merged. Goku and Kushina meet under these strange circumstances and have to figure out how to deal with the chaos that ensues while also exploring their new - found feelings for each other. This could involve battles against powerful villains who want to take advantage of the merged universes, and Goku and Kushina would be at the forefront of protecting their new world together.
One possible plotline could be them going on an adventure together, facing some common enemy and growing closer in the process.
One possible plotline could be them getting stranded on an uncharted island. They have to rely on each other's skills to survive. Luffy's strength and Bonney's ability to manipulate ages could be crucial in finding food, building shelter, and fighting off any threats on the island.
One possible plotline could be that Cynthia and Steven team up to face a new and powerful threat in the Pokemon world. They might start off as rivals, each thinking they have the best way to deal with the situation, but gradually come to respect and rely on each other.