It could be a story where Naruto grows up in the Fairy Tail world instead of the Hidden Leaf. Since Erza is known for her strict but caring nature, she would probably train Naruto really hard. Naruto might have a different set of values influenced by the Fairy Tail guild. He could also make some new friends among the Fairy Tail members and together they could face powerful enemies. His ninja way might get a new interpretation in the context of the Fairy Tail universe.
A fanfiction like this would likely involve Naruto having to deal with the differences between the two worlds. Erza's world is full of magic, while Naruto's original world is based on chakra. He might struggle to fit in at first. However, his natural ability to make friends and his never - give - up attitude would help him. His relationship with Erza as his mother would be complex. She would be protective but also expect a lot from him. And his journey to become a great ninja - magician hybrid would be full of challenges and self - discovery.