Naruto, of course, is central. Happy, the blue Exceed from Fairy Tail, could play a significant role. He could be Naruto's sidekick, providing comical relief and also helping him understand the Fairy Tail world better. And then there's Gildarts. As one of the strongest mages in Fairy Tail, he could take Naruto under his wing and train him in some of the more advanced and dangerous forms of magic, making Naruto a formidable force in the fanfiction world.
Well, Naruto is a given as the main character who is being raised in the Fairy Tail environment. Gray would be an interesting addition. His cool - headedness could contrast with Naruto's sometimes impulsive nature. Erza would also be a key character. She could be like an older sister figure to Naruto, teaching him discipline and how to handle difficult situations, both in battles and in the guild.
For this fanfiction, Harry Potter is the main focus, but from Fairy Tail, Makarov Dreyar could be a key character. As the guild master, he could be like a father figure to Harry, guiding him in his growth and development in the Fairy Tail world. Wendy Marvell could also be a main character. Her healing magic and gentle nature could be a great influence on Harry. And Happy, the blue flying cat, could be Harry's sidekick, adding some comic relief and also helping him out in various situations with his unique abilities.
Another possible main character could be Erza from Fairy Tail. She is a strong and respected member of the guild. Her leadership skills and combat abilities could be crucial in the story. She might initially be skeptical of Naruto but then come to respect him as he proves his worth as a guardian. And Naruto himself would have his own set of friends and allies from his world that could potentially make appearances or be mentioned, like Sasuke or Kakashi, even if they are not directly in the Fairy Tail world, their influence on Naruto could still play a part in the story.
Obviously, Naruto would be one of the main characters. And probably some of the key Fairy Tail characters like Natsu, who is known for his fire - dragon slayer magic, and Lucy, who uses celestial spirit magic. They are likely to interact with Naruto in the fanfiction.
In many 'naruto fairy tail master fanfiction' stories, characters like Sasuke from Naruto and Gray from Fairy Tail also play important roles. Sasuke's brooding nature and powerful Sharingan abilities, combined with Gray's ice - make magic, can create some interesting dynamics. They might be rivals at times, or they could end up working together against a common threat that emerges from the merging of the two universes.
Storm Fullbuster, son of Gray and Juvia. He could have a unique blend of ice and water magic. His story could revolve around him trying to live up to his parents' legacies while also forging his own path in the guild.
Natsu could be a main character. He could be the hot - headed but kind - hearted student who always gets into trouble but also manages to save the day with his powerful fire magic. His loyalty to his friends would be a key aspect in the fanfiction.
It could be Natsu. He's hot - headed and might not understand Naruto's ways at first. He could see Naruto as a threat to his position in the Fairy Tail guild and start bullying him to assert his dominance.
The main antagonist could be a powerful demon that has been sealed in the Fairy Tail world for a long time. Naruto's arrival disrupts the seal somehow, and the demon sees Naruto as a key to fully breaking free. The Fairy Tail members and Naruto must put aside their differences and combine their powers to fight this demon.
It could be a dark wizard from the Fairy Tail world who sees Naruto as a threat because of his unique powers. This wizard might try to stop Naruto from leaving, fearing that he'll take the knowledge of Fairy Tail's magic to other places.
It could also be a new character entirely. This character could be a hybrid of the two worlds, having some ninja abilities and some magic powers. Being a unique being, they would attract the attention of female characters from both Fairy Tail and Naruto. This new character's journey of self - discovery and their attempts to bridge the two worlds could be the central plot, with the harem aspect adding a romantic sub - plot.