Perhaps the story focuses on the girl's journey to master the guitar as a new form of magic. She might face challenges like finding the right strings that can withstand her magic energy. Along the way, she could meet other musicians in the Fairy Tail world who teach her different tunes with unique magical effects.
The fanfic could also be about a girl from Fairy Tail who uses the guitar to communicate with spirits. The guitar's music is like a language that only spirits can understand. She then forms an alliance with these spirits to help Fairy Tail in a big conflict against a powerful dark guild. The girl has to learn different melodies to call upon different types of spirits, and she has to deal with the distrust some of her guild mates initially have towards these spirit allies.
Erza might be an interesting main character for this fanfic. Given her strong will and combat skills, she could incorporate the guitar into her fighting style. For instance, she could use the guitar as a weapon, slashing enemies with the sharp edges of it while also using its music to disrupt their magic.
The girl OC could have been a street performer before joining Fairy Tail. Her guitar was her only means of survival. One day, she witnessed a Fairy Tail mage doing a great deed. Inspired, she decided to seek out Fairy Tail. The guitar has seen her through tough times on the streets, and now in Fairy Tail, it becomes a symbol of her journey from being alone to being part of a big family. She uses the music from her guitar to tell her story to the other members of the guild.
There was a girl in the Fairy Tail world. She was an original character (OC) named Aria. Aria carried a beautiful guitar everywhere. Her guitar was not just an instrument but also a symbol of her power. When she played it, she could influence the emotions of those around her. In a battle against a dark guild, Aria used her guitar to boost the morale of the Fairy Tail members. She played a rousing tune that filled them with courage. The unique melodies she created with her guitar made her a beloved figure in the Fairy Tail guild.
In a 'pokemon trainer in fairy tail fanfic', the trainer may be on a quest to find a way back home. Along the way, they share their knowledge of Pokemon with the Fairy Tail guild. This could lead to some members wanting to catch Pokemon of their own. The trainer might also have to adapt their Pokemon training methods to the different magic - based rules of the Fairy Tail world.
One possible plot could be that Ben Tennyson somehow ends up in the world of Fairy Tail. He could team up with Natsu and his friends to fight against a common enemy. Ben could use his alien forms to combat the dark magic threats that Fairy Tail often faces.
The plot might involve a powerful magical item that exists in both universes. In the fanfic, characters from both Rave Master and Fairy Tail could be in a race to obtain this item. For example, Elie from Rave Master and Lucy from Fairy Tail might have some sort of rivalry or partnership in the search for it. And along the way, they discover that the item has the power to either save or destroy both worlds.
The plot could involve Naruto trying to find a way back to his own world. In the process, he teams up with Fairy Tail to fight a common enemy. His chakra-based attacks could be a new and interesting element in the Fairy Tail battles. For example, his Rasengan might be seen as a super - powerful magic spell by the people in the Fairy Tail guild. He could also form new friendships and rivalries within the guild.
One possibility is that it's a fanfic set in an alternate universe where Sting has a special connection with Lucy. They might discover a new form of magic together. For example, Sting's white dragon slayer magic could combine with Lucy's celestial spirit magic in an unexpected way, leading to a whole new set of adventures.
Well, perhaps the fanfic could focus on a magic item in Fairy Tail that has a connection to the Kamui power from Naruto. A group of Fairy Tail wizards and a Naruto character team up to figure out the secrets of this item. They might face challenges like rival guilds trying to steal the item and ancient spells that are linked to the Kamui - like power. As they go on this adventure, they also learn about each other's worlds and grow as a team.
One idea could be that Ben Tennyson somehow gets transported to the Fairy Tail world. He could team up with Natsu and the gang to fight a common enemy that has the power to absorb alien DNA like Ben's. They would combine their different powers and fighting styles to take on this new threat.