Maybe when Lucy goes home, she discovers a long - lost family heirloom that has some sort of magical power. This leads her on a new adventure as she tries to figure out what the heirloom is for and how it might be related to her celestial magic. She could consult the guild's library and some of the older members for help.
Well, in the fanfiction, perhaps Lucy goes skinny dipping after a really tough battle. She feels the need to cleanse herself, both physically and mentally. As she's in the water, she might start reminiscing about her journey in Fairy Tail. And who knows, she could accidentally activate some kind of water - based magic that she didn't know she had. This could then set off a whole new adventure for her and the other members of Fairy Tail.
There could be a wandering mage at her home. This mage might be on the run from some powerful enemy and has sought refuge at Lucy's place. Lucy then has to decide whether to help the mage or turn them in, all while dealing with the potential danger this might bring to her and her family.
Well, one possibility could be that it's a really innocent situation. Maybe they got into some kind of magical mishap that made them dirty and the only available place to clean up was a shared shower area. But they're both really embarrassed and trying to be respectful of each other's space while also dealing with the comical aspect of the situation.
Well, it could start with Natsu barging into the bathroom thinking it's unoccupied, only to find Lucy already in the bath. There could be a lot of blushing and yelling from Lucy. Then, they might have to figure out how to get Natsu out without alerting the whole guild. Or perhaps, it could be a magical accident that causes them to end up in the same bath, and they have to work together to reverse the spell while dealing with their embarrassment.
One possibility could be that it's a comical situation. Maybe they got into some kind of magical mishap that left them dirty and the only available place to clean up was a small bathroom where they had to share the shower in a very awkward way. Natsu, being his clueless self about social norms, doesn't really understand the awkwardness at first while Lucy is blushing like crazy.
One idea could be that Jackal, after some soul - searching, decides to turn over a new leaf and teams up with Lucy. They could go on a mission to retrieve a powerful magical artifact that was once used by an ancient dark wizard. Along the way, Jackal's knowledge of the dark arts helps them navigate through various traps, while Lucy's celestial magic provides the offensive and defensive power they need.
One possible plot could be that Lucy and Juvia leave Fairy Tail to go on a self - discovery journey. They might want to explore their individual magic powers more deeply without the constraints of the guild. Maybe they travel to different magical realms, meet new characters, and learn unique magic techniques that they can bring back to Fairy Tail later.
One possible plot could be that Midnight uses his magic to trap Lucy in a dream - like world. In this world, he challenges her to various magical tasks. As they interact more, Lucy starts to understand Midnight's past and the reasons behind his actions. Eventually, she manages to break free from the dream world using her Celestial Spirit magic and in the process, Midnight has a change of heart and decides to turn away from his evil ways.
In this fanfiction, perhaps Lucy joins Fairy Tail right after she discovers her magic abilities. This would change a lot of the initial interactions. She could be more naive and inexperienced when joining, which would lead to different dynamics within the guild. Like, she might be more reliant on the others for guidance in using her magic, rather than having some basic skills already when she actually joins in the original story.
Perhaps in this fanfiction, the school they go to is a special school for different guilds. The Fairy Tail group is there to learn about the history and politics of the magical world. They discover secrets about their own guild's past through the school's archives. Natsu accidentally sets off an old magical trap while exploring the restricted section of the library. This leads to a series of events where they have to work together with students from other guilds to fix the mess. Gray and Natsu have to put aside their usual bickering, and Lucy uses her wits to figure out how to reverse the effects of the trap.