It could develop in a rather unexpected way. Suppose there's a magical accident that causes their minds to be linked for a short time. They get to see each other's deepest fears and desires. This experience could make them more empathetic towards each other. After that, Mystogan might be more protective of Wendy, and Wendy could be more understanding of Mystogan's often - mysterious ways. Their relationship could then evolve from a simple acquaintance in the guild to a pair that has a special connection that is unique to them.
There could be a fanfiction where Mystogan has a premonition about a future threat to Wendy. He then decides to secretly protect her. Along the way, Wendy discovers what he's doing and they have a heart - to - heart. This could lead to a development of romantic feelings between them, or at least a very strong platonic bond as they face the impending danger together.
If in an alternate universe, Mystogan was raised in a different guild and Natsu was sent to bring him back to Fairy Tail. Natsu would initially be frustrated with Mystogan's aloofness. However, as they travel together, Natsu would learn about Mystogan's past and the reasons for his detachment. This understanding could lead to a friendship developing between them, and in the end, Mystogan might decide to join Fairy Tail because of Natsu's influence.
Their relationship could develop through training sessions. As they train together, they learn more about each other's strengths and weaknesses, and a bond of mutual respect forms.
Their relationship might develop in a more emotional way. Maybe one of them gets injured during a battle, and the other is extremely worried. This concern could make them realize how much they care for each other. They could then start to open up about their fears and dreams, which would bring them closer together. They might also discover that they have a lot in common in terms of their goals within the Fairy Tail guild.
In a fan - made story, their relationship could develop through shared goals. For example, if there is a threat to the Fairy Tail world that only their combined powers can stop. As they work together towards this goal, they start to understand each other better. Zeref might be softened by Lucy's optimism and determination, and Lucy might see the good in Zeref that is buried deep beneath his dark exterior. This could lead to a relationship filled with mutual respect and love over time.
At first, their relationship might be one of mutual curiosity. Naruto would be intrigued by Wendy's magic, and Wendy would be fascinated by Naruto's ninja abilities. As they face challenges together, they would start to trust each other more. For example, if they are in a battle against a strong enemy, Naruto would rely on Wendy to back him up with her support magic, and Wendy would depend on Naruto's combat skills.
Natsu would also be an interesting choice. Natsu's brash and impulsive nature could contrast well with Mystogan's more reserved and calculated personality. They could start off not getting along but then grow to respect each other during a difficult quest.
In some Fairy Tail fanfictions, Natsu and Wendy might be depicted in a romantic relationship. However, this isn't a common or canon relationship in the original Fairy Tail series. Fanfiction writers often explore different pairings for creative and imaginative purposes.
In many fanfictions, Wendy and Lucy's relationship is developed when they help each other with their magical training. Wendy might teach Lucy about some of her unique dragon - slayer magic techniques, and Lucy could share her celestial spirit knowledge with Wendy. As they learn from each other, they become closer. Also, there could be situations where they protect each other from the judgment or jealousy of other guild members, which cements their relationship further.
There are stories where Wendy uses her sky magic to enhance Natsu's senses. Since she has a connection to the sky, she can heighten Natsu's vision or hearing, which helps him in a battle. And in return, Natsu protects Wendy from any close - range attacks while she's using her magic to support him, creating a symbiotic relationship between their powers.