One common theme is friendship turning into something more. Their initial comradeship in the Survey Corps often develops into deeper feelings. Another theme is sacrifice. Given their dangerous world, they might sacrifice for each other. Also, trust is a big theme as they have to trust one another in battle and in their personal relationship.
It's not a true story. Usually, such titles are used for fictional tales crafted to engage and entertain readers rather than being based on real events.
Percy as Zoe's father in fanfic could be a really interesting concept. If it's in a fan - made story, perhaps Percy has certain traits that are passed on to Zoe. Maybe he's a heroic figure, and Zoe inherits his courage. But again, we need to know more about the fanfic. Is it based on a fantasy world? A sci - fi setting? That would change how we view Percy and his role as Zoe's father.
One possible fanfiction could be about Ash and Zoe teaming up in a world where Pokemon and Digimon co - exist. They might start off as rivals, with Ash's Pokemon training skills and Zoe's understanding of Digimon clashing. But as they face a common threat, like an evil organization trying to use both Pokemon and Digimon for bad purposes, they gradually learn to work together. Ash could teach Zoe about the bond between a trainer and a Pokemon, while Zoe could introduce Ash to the unique digital world of Digimon.
Love is a very common theme. Their budding romance and how it develops over time is often explored. For example, in many fanfictions, they start as friends and gradually realize their deeper feelings for each other.