They could go on a quest to find a powerful magical artifact. Naruto's combat skills and Lucy's knowledge of magic could be useful in navigating dangerous dungeons and fighting off enemies who also want the artifact.
They could have an adventure where they have to stop an evil wizard who is stealing chakra and magic energy. Naruto uses his ninja skills and Lucy uses her celestial spirit magic to track down the wizard and defeat him.
Well, for starters, they could embark on an adventure to protect the Sohma family from outside threats. Naruto, with his Rasengan and other jutsu, would be a formidable protector. They might also travel to hidden ninja villages together, with Tohru learning about Naruto's world. Or perhaps they go on a quest to uncover the secrets of Tohru's mother, and along the way, they encounter all kinds of challenges, like dangerous yokai or other ninja clans who are interested in the Sohma family's unique situation.
They could go on an adventure to find a powerful treasure that combines the power of the One Piece and some kind of ninja - related artifact. Maybe they'd have to fight against a new enemy that is a combination of pirates and rogue ninjas. They might travel to new islands where Naruto's ninjutsu would be useful for exploring hidden caves, and Luffy's stretching ability would help them reach high places or cross large gaps.
They might have adventures where Naruto's brotherly instincts lead the way. Maybe they go on a mission to protect a village that has a special meaning to Naruto as a 'brother' figure to Team 7. He would be extra determined to keep it safe.
This could be an interesting fanfiction concept. Naruto's energetic and determined personality would contrast with Lucy's more elegant and sometimes sassy nature. Maybe Naruto could use his ninja skills to protect Lucy in the Fairy Tail world, adding a whole new dynamic to the story.
In 'naruto lucy brother fanfiction', a prevalent theme is often the exploration of different powers. Naruto has his ninja abilities and Lucy's brother might have some unique powers in the fan - made world. They could learn from each other or combine their powers to overcome challenges. Also, themes of loyalty and family values can be present. Since Naruto values his friends like family, he may extend that to Lucy's brother, and loyalty between them could be a major aspect of the story.
Maybe they embark on an adventure to help a small, oppressed village. They use their combined skills to overthrow the tyrant ruling the village and then stay for a while to help rebuild it. During this time, they learn about different ways of life and make new friends. This adventure would strengthen their bond and also their reputations as great shinobi.
Lucy would likely be very worried about Naruto. She might feel abandoned at first, especially if she doesn't know the reason behind his running away. She could also be in danger if Naruto was protecting her from something. Without him around, she would have to fend for herself or rely on other friends or family members.
They could have adventures where they explore different dimensions. Naruto's ability to travel through his world could be combined with Ben's inter - galactic travels using the Omnitrix. They might end up in a dimension full of strange creatures and have to fight their way out together.
She could have adventures where she uses her Pokemon to explore new areas in the Fairy Tail world that are too dangerous for normal mages to go alone.