Perhaps the 'joey x rattata fanfic' could be set in a world where Rattata are extremely rare. Joey, a Pokémon trainer, goes on a quest to find a Rattata. Along the way, he discovers the unique abilities of Rattata and how it can change his whole training strategy.
Joey could start as a timid trainer and become more confident as he bonds with Rattata. Rattata, on the other hand, might start off as a wild and skittish Pokémon but become more loyal to Joey over time.
Another theme is self - discovery. As they interact more, both Kaiba and Joey often learn more about themselves. In some fanfics, they realize that the qualities they hated in each other are actually things they can learn from. It's like a journey of personal growth for both of them.
One common theme is rivalry - their long - standing competitive nature in the Duel Monsters realm. This often serves as a starting point for the relationship to develop.
A common theme could be the exploration of their relationship dynamic. Given their different personalities in the original Yu - Gi - Oh! series (assuming they are from there), fanfics might focus on how they overcome their differences. For example, Seto's cold and calculating nature vs Joey's more hot - headed and impulsive one.
One common theme could be friendship evolving into something more. Since they start as friends in the original show, fanfics might explore how that relationship deepens romantically. Another theme could be the struggle with their new - found feelings, like how they deal with the reactions of their other friends, like Ross or Phoebe.
I'm not really into that kind of fanfic, but you could try searching on some popular fanfic websites like Archive of Our Own. There might be a whole bunch of 'joey x chandler' fanfics there, and you can filter by the tags to find the ones that suit your taste.
You can try looking on some popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics from various fandoms, and there's a good chance you'll find some great 'joey x daniel fanfic' there.
There are also 'joey x daniel fanfic' stories that are set in a school environment. For example, they could be classmates who start out not getting along but then gradually become best friends through a series of school projects and events. They learn about each other's strengths and weaknesses and support one another.