Maybe Lucy is a non - ninja sister who Naruto has to protect. But she has a special knowledge or a key to an ancient power. As Naruto tries to keep her safe from the villains in the Naruto universe who want to use her for their own gain, they develop a strong bond and learn more about their family history.
A possible plot could be that Lucy was experimented on by Orochimaru in the past. She managed to escape and now she's on a quest for revenge. Naruto, upon learning she's his sister, decides to help her. Along the way, they encounter many challenges and also uncover secrets about Naruto's own past and the Uzumaki clan.
One possible plot could be that Lucy is a long - lost sister of Naruto. She has been living in a different village all this time and has unique ninja abilities. When they finally meet, they have to work together to face a common enemy that threatens both their villages.
The plot could involve Naruto being sent to Fiore as part of a diplomatic mission on behalf of the Hidden Leaf Village. There, he meets Lucy at the Fairy Tail guild. At first, the members of Fairy Tail are a bit skeptical of Naruto. But Naruto's determination and his cool ninja abilities start to win them over. Lucy and Naruto bond over their shared experiences of losing loved ones. They then go on an adventure together to stop a dark force that is threatening both their worlds.
Well, perhaps in a fanfiction, there is a powerful magic that links the Naruto universe and the Fairy Tail universe where Lucy is from. Naruto is on a mission to understand this new magic when he meets Lucy. They initially have misunderstandings but as they learn about each other's worlds and goals, they start to fall for each other. The kiss could be a moment of realization of their feelings during a battle where they protect each other. This kind of plot would blend the elements of both universes in an exciting way.
One possible plot could be that Lucy, from another dimension or world, accidentally ends up in the Naruto universe. Naruto, being the curious and friendly ninja he is, befriends her. As they go on adventures together, they gradually develop feelings for each other and end up sharing a kiss. Maybe they have to face some common enemies or overcome cultural differences along the way.
Well, one possibility is that Naruto uses his ninja skills like shadow clones to distract the enemies that are after Lucy. He could then use his Rasengan to break through any barriers between Lucy and safety.
Perhaps it's a story where Lucy is in love with someone she can't be with publicly. So she writes this secret fanfiction to express her feelings and desires about that relationship.
One possible plot could be that Lucy and Laxus accidentally end up having to take care of a baby together. Maybe they find a lost baby during one of their guild missions. At first, they're both really clumsy and unsure of how to handle it. But as time goes on, they start to develop a bond not only with the baby but also with each other in a new, more family - like way.
One possible plot could be that Lemon, Naruto's sister, discovers some hidden jutsu that Kushina once knew. Naruto and Lemon then train together to master it. Along the way, they face challenges like other ninja clans trying to stop them as they fear the power of this new - found jutsu. And in the end, they use the jutsu to protect their village and honor Kushina's memory.
One possible plot could be that Naruto is somehow transported to the Fairy Tail world where he meets Lucy Heartfilia. They could team up to fight a common enemy that threatens both their worlds. Naruto's unique ninja skills combined with Lucy's celestial spirit magic would make for some epic battles.
Well, perhaps Natsu could be sparring with Lucy and accidentally land a more powerful blow than he intended during a training session. Maybe he's in his dragon force mode and loses control for a second, hitting Lucy hard enough to make her fall and get injured.
It could also be that the sister, in an attempt to help Naruto, gets involved with some dangerous characters or situations. Maybe she tries to find someone powerful to plead Naruto's case, but that person has some ulterior motives. This would add a lot of twists and turns to the story, as Naruto then has to not only deal with his own problems but also save his sister from the trouble she has gotten into while trying to help him.