One popular story might be 'A Barian's Heart'. It focuses on the complex relationships between the characters. It delves into how love can develop between a Zexal character and a Barian in a really engaging way.
First, you need to understand the characters well. Know their personalities, backstories, and powers from the original Yu - Gi - Oh Zexal series. This will help you create believable relationships. For example, if you're writing about a Barian who is usually seen as cold, you need to find a way to make their falling in love seem natural.
Another concept is a fusion of their powers. Suppose a villain creates a device that combines the power of the tailed beasts from Naruto and the Numbers from Yu - Gi - Oh Zexal. The heroes from both universes have to work together to stop this new threat. Yuma could use his ability to communicate with his monsters and Naruto could use his Sage Mode to sense the new evil power.
One possible fanfiction could involve Yuma being kidnapped by an unknown group who are after his powerful Xyz Monsters. They might hold him captive in an abandoned warehouse and try to force him to give up his deck. But Yuma, being the brave duelist he is, uses his wits and the bond with his Astral to find a way to escape and turn the tables on his captors.
First, understand the characters from both series well. Know Naruto's determination and his growth throughout the series, as well as Yuma's courage in Yu - Gi - Oh Zexal. Then, create a unique plot that combines elements from both universes in a logical way. For example, you could have a tournament where both ninja skills and dueling skills are required to win.
One possible fanfiction could be about an Arclight family member getting involved with a vampire in the Yu - Gi - Oh Zexal universe. Maybe a young Arclight discovers a hidden vampire clan and has to either fight them or make an alliance. It could be a story full of mystery and action, with card duels taking on new twists as vampire - related cards come into play.
One possible fanfiction could be about Yuma and Dark Mist forming an unexpected alliance. Maybe Dark Mist has some hidden motives that initially seem malicious but as the story progresses, it turns out he's actually trying to protect Yuma from a greater evil in the Zexal world.
A common theme is self - discovery. The OCs often start as unknowns in the Zexal world and through their dueling experiences, they learn more about themselves. Another theme is friendship. They form bonds with the existing characters like Yuma and his friends.
Another theme is friendship. When characters from different series meet, they usually form new friendships or strengthen existing ones. This is often shown through them working together in duels or facing challenges as a team. In a lot of these fanfictions, you'll see Zexal characters and characters from other Yu - Gi - Oh shows bonding over their shared love for dueling.
One possible fanfiction could be that Yuma and Tori start off as friends. As they go on more adventures in the Yu - Gi - Oh Zexal world, they gradually realize their feelings for each other. For example, during a tough duel, Tori's words of encouragement make Yuma see her in a new light. They might then have some sweet moments together, like sharing a meal after a victory and realizing that their bond is more than just friendship.