Erza from Fairy Tail could also be a main character in this type of fanfiction. She is strong, independent, and has a complex personality. In a Naruto x Fairy Tail crossover, she could form a harem of her own, with Naruto characters being attracted to her strength and Fairy Tail characters having their own relationships with her. Her leadership skills and magical abilities would play an important role in any story that unfolds.
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.
It could be Naruto himself. Imagine Naruto, after achieving some sort of ultimate power in his own world, is transported to the Fairy Tail world. His energetic and kind - hearted nature would attract the female characters in Fairy Tail, like Lucy, Erza, etc. His ninja skills would be a novelty in that world and his godlike powers would make him stand out, leading to the formation of a harem.
Gray could be the main character in a harem fanfiction. His cool exterior and his ability to use ice magic in such a unique way make him stand out. He has a bit of a rivalry with Natsu which could add an interesting dynamic to the harem. Characters might be attracted to his brooding nature and his underlying loyalty to his friends and the guild.
Lucy could also be a great main character. She's already smart and strategic. With the addition of a gamer ability, she could use her celestial spirit keys in more creative ways. For example, she could unlock new forms or powers for her spirits by completing in - game - like quests related to them. She might also be able to manage her magic energy more efficiently, like a gamer manages resources.
Perhaps a plot where a powerful villain threatens both the Naruto and Fairy Tail universes. The characters then combine their skills, like Naruto's ninjutsu and Fairy Tail's magic. In the harem part, it could be that the main character, say a new character created for this fanfiction, has to navigate the different personalities and affections of characters from both series while they all work towards saving their worlds.
One common theme is the power combination. Since Naruto has his ninja powers and Fairy Tail characters have magic, seeing how these powers interact and combine in the harem scenario is often explored. For example, Naruto might use his shadow clone jutsu in a new way with the help of Fairy Tail magic.
The main characters could also be Sasuke from Naruto and Gray from Fairy Tail. Sasuke's cool and brooding nature combined with his Sharingan abilities would be a draw. Gray's ice - make magic and his habit of accidentally stripping could add some humor. In the harem, characters like Ino from Naruto and Levy from Fairy Tail could be part of it. Ino's mind - control jutsu and Levy's intelligence with books and runes would bring different elements to the story.
It could be a new character created specifically for this fanfiction. This character could be a young water dragon slayer who gets lost between the two worlds. They would be the main focus as they try to adapt to the Naruto world while still having their Fairy Tail powers.
One popular pairing is Naruto and Lucy from Fairy Tail. Naruto's determination and Lucy's intelligence and magical abilities make for an interesting combination. Another is Sasuke and Erza. Their strong - willed and somewhat aloof personalities can create a lot of tension and potential for character development in the fanfic. And then there's Kakashi and Mirajane. Kakashi's laid - back yet highly skilled nature paired with Mirajane's kind and powerful self can be quite appealing.
It could be Sasuke. Since he has the Sharingan which is related to the Kamui ability in a way. He could be transported to the Fairy Tail world and his brooding and powerful nature would make for an interesting dynamic as he tries to find his way back home while getting involved in Fairy Tail's affairs.