It could lead to a change in the guild's dynamics. Naruto has his own unique combat style and abilities. His departure might make the guild realize the need to diversify their fighting strategies. For example, they might start to look for members with skills similar to Naruto's ninja techniques.
She would fit in very well. The Fairy Tail guild is all about family and acceptance. Given her parents are Lucy and Natsu, she'd be welcomed with open arms. She could learn from the older members like Makarov and Mirajane, and bond with the younger ones like Romeo. Her magic skills would also contribute to the guild's strength during battles or when helping the town.
The guild would become more protective. Members like Gray and Lucy would probably offer their help in various ways, like helping with baby - proofing their living quarters or giving advice on parenting. It would also add a more family - like atmosphere to the guild. There would be more anticipation and excitement for the new arrival.
In many fanfictions, when Wendy is hurt, it unites the Fairy Tail guild. For example, they might all come together to find a cure if she's been poisoned or injured by a special magic. Her hurt makes everyone more determined to protect each other.
A common plot twist is the betrayal of a seemingly loyal guild member. This could be someone who has been with the guild for a long time but has a hidden agenda. Another is the sudden appearance of a long - lost relative of a main character who has a major impact on the guild war. For example, a long - lost brother of Natsu showing up with a powerful new form of dragon - slayer magic.
A common theme is the combination of different power systems. Since Naruto has ninja skills and chakra, and Fairy Tail has magic, fanfics often explore how these two power systems interact within the context of a thieves guild. For example, a character might use ninja stealth to steal a magical artifact from a Fairy Tail - like guild.
Fairy Tail would be a mix of reactions. The younger members would be thrilled and look up to Naruto as a hero. The older and more experienced members would assess his skills and how he could fit into the guild. They might also be a bit protective of their way of life in the guild at first, but as they get to know Naruto better, they would accept him as one of their own.
You could make an OC guild that is a rival to Fairy Tail at first but then has to team up with them to face a common enemy. The OC in this guild might have a grudge against Fairy Tail initially because of a misunderstanding. For instance, they think Fairy Tail stole a powerful magic artifact from their guild long ago. But as they work together, they realize that they were wrong and form strong bonds with the Fairy Tail members.
Some of the more cautious members, like Erza, might be a bit wary at first. She would be concerned about how Igneel's presence might change the power dynamics within the guild and what his intentions truly are. But over time, as she sees his positive influence, she would likely warm up to him.
In my opinion, Makarov could be the ideal Fairy Tail guild master in game fanfiction. He has great leadership skills and a strong sense of justice. His magic power is also quite formidable, which can add a lot of exciting elements to the game.