Some fanfictions might show them having adventures within the village itself. For instance, they could be on a mission to solve a mystery that's been plaguing the village, like a series of strange disappearances. Naruto would use his detective skills, which he's developed over the years, and his siblings would learn from him as they go along.
Maybe they embark on a journey to save their respective worlds from a common threat. A powerful demon or an evil wizard is trying to destroy both the Naruto universe and the Fairy Tail world. Naruto and Natsu would travel across different dimensions, gathering allies from both worlds. Naruto would use his Rasengan and Natsu his Fire Dragon's Roar to fight off hordes of minions while they search for a way to stop the main villain.
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, sometimes he's depicted as a fun-loving older brother. He'll play pranks with his siblings but also be there when they need him. His status as a hero in the village gives his siblings a sense of pride, and he uses that to boost their confidence. He might take them on adventures around the village, showing them all the secret spots he found when he was younger.
They could go on a journey to find out more about their family history. Maybe there are secrets about their parents that they need to uncover. Along the way, they would face various enemies and challenges. Naruto's combat skills and Tayuya's unique jutsu would be put to the test as they protect each other.
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.
One possible adventure could be a journey to find a lost artifact that is crucial for the safety of the princess's realm. Naruto, with his experience in exploring and his sense of direction, would lead the way. Along the journey, they would encounter various obstacles like dangerous terrains and mythical creatures. Princess Serenity would use her wisdom and diplomatic skills to deal with some situations, while Naruto uses his brute force when necessary. This would strengthen their bond as siblings and heroes.
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 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.
In a fanfiction where they are siblings, new adventures could abound. They might embark on a journey to find a long - lost family heirloom that has special powers. Since they are siblings, they would have a unique bond that could help them face the challenges along the way. They could also take on missions together that are more focused on family - related issues, like rescuing a kidnapped family member or uncovering a conspiracy that affects their family name.
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.