Perhaps in this fanfiction, Leah has a special power that Naruto needs to learn in order to defeat a new and powerful foe. Naruto starts training with Leah. Along the way, they learn about each other's pasts, their dreams and fears. As Naruto masters the power, they also form a bond that is unbreakable. And this bond could be the start of a new relationship, whether it's a romantic one or a very strong friendship.
One possible plot is that Leah is from a different village and she comes to Konoha. Naruto is assigned to show her around. At first, Naruto is his usual boisterous self and Leah finds it annoying. But then they discover a common enemy that is threatening both their villages. They then combine their unique skills, Naruto's Rasengan and Leah's special elemental magic (assuming she has some in this fanfic), to defeat the enemy and in the process, fall in love.
Leah could be a new ninja from a far - off land that has unique abilities. Maybe she has the power to control time or something really extraordinary.
Well, it could be that Leah, for some reason, has a strong mental or emotional connection (the imprinting) with Naruto. Maybe she sees his determination and is drawn to it. She might start to follow his ideals and even develop a friendship or more with him in the fanfiction world.
It could be that Leah is a shy person and Nahuel is the more outgoing one. They meet by chance in a park. As they start to know each other better, Nahuel slowly breaks down Leah's walls. The kiss is a culmination of their growing connection, and after that, they have to figure out how to build a relationship with their different personalities.
The plot might involve Leah finding out she's pregnant and then trying to figure out who the father is. If it's in the context of the Twilight universe, there could be added complications like how the werewolf nature affects the pregnancy and the unborn child. She could also be worried about the safety of her baby considering the various supernatural threats in that world.
Maybe the story could be about how Leah's imprint on Edward changes her. She could become more determined to bridge the gap between werewolves and vampires. For example, she might try to convince the other werewolves that not all vampires are bad because of her newfound connection to Edward. And Edward, in turn, might start to see the werewolves in a different light. It could also involve them facing external threats together, which forces them to rely on each other.
In a 'naruto x leela fanfiction', it could be that there is a threat that endangers both their worlds. Naruto and Leela are brought together by some sort of prophecy. As they work together, they also have cultural exchanges. Naruto is fascinated by Leela's Futurama - like world with its strange creatures and advanced tech, while Leela is intrigued by Naruto's ninja village and the concept of chakra.
One possible plot for a 'naruto x ashley fanfiction' could be that Ashley is a lost traveler in the Naruto universe. Naruto finds her and decides to help her find her way back home. Along the way, they face various challenges like battling rogue ninjas. As they overcome these challenges, they develop a deep bond. Ashley also starts to understand the ways of the ninja and Naruto is exposed to new ideas from Ashley's world.
Well, one possible plot could be that Naruto, while on one of his travels, stumbles upon a strange dimension where he meets Astolfo. Astolfo's unique abilities and Naruto's ninja skills could combine in some crazy adventures. They might have to fight against a common enemy that threatens both their worlds. Maybe they start off as strangers but gradually become friends as they learn from each other's strengths.
Well, it could be that Naruto is on a mission and accidentally stumbles into Persephone's domain. At first, they might be at odds, as they come from very different worlds. But then, as they get to know each other, they find common ground in their experiences of being in situations they didn't fully choose. Naruto could teach Persephone about the power of friendship, and she could teach him about the mysteries of the underworld.
Well, one possible plot could be that Naruto somehow gets transported to the Mario universe where he meets Rosalina. They could start off as strangers, but then Naruto's determination and kindness draw Rosalina's interest. Maybe they team up to face a common threat that is endangering both the ninja world and the Mario universe.