One possible reason could be a misunderstanding. Maybe someone framed Lucy for something she didn't do, like stealing a powerful magic item from the guild. Another reason might be that she accidentally broke a very important and unbreakable guild rule without realizing it. For example, if there was a rule about not using a certain type of dark magic, and she unknowingly used it to save a friend.
Happy would be sad and confused. He doesn't like to see his friends in trouble. He would fly around trying to gather information from different guild members. He would also stay by Lucy's side, trying to cheer her up. And all of her other friends in Fairy Tail would at least have some doubts about the decision. They know Lucy's character, and her sudden expulsion would make them question whether the guild made the right choice.
One possible reason could be a misunderstanding. Maybe someone framed Natsu for a crime he didn't commit, like stealing a powerful magical item from the guild. And the guild, without proper investigation, decided to kick him out. Another reason might be his recklessness. If his actions put the guild in great danger too many times, the guild masters could decide that he's a liability and kick him out.
Well, for one, it's the unique way the author can incorporate her singing into the existing Fairy Tail lore. For example, if they connect her celestial magic to her singing in a new and creative way. Like her spirits being able to enhance her voice or her singing having the power to summon special magic.
Natsu would probably be very angry at first. He loves Fairy Tail like a family, so being kicked out would feel like a huge betrayal. He might go on a rampage, shouting and arguing with the guild members who made the decision.
Maybe he got into too many fights. Natsu has a short temper and if there were other students in the academy who provoked him or if he was standing up for someone, he might have engaged in brawls that the academy doesn't tolerate. In a place like Fairy Tail Academy, they might have strict rules about student behavior regarding fighting.
One possible reason could be that he's framed for a crime he didn't commit. Maybe someone planted false evidence to make it seem like he was endangering the guild. Another reason might be that his power got out of control and the guild, fearing for the safety of its members, made the tough decision to kick him out.
If Lucy never joined Fairy Tail, the friendships and relationships among the characters would form in a very different way. Also, many of the story arcs might not unfold as they do in the original plot.
Well, if Natsu asks Lucy out in fanfiction, it could change the whole dynamic of the Fairy Tail group. Their friends would probably be super supportive, especially Happy. They could start exploring new places not just for quests but also for romantic getaways. And Lucy might write a new story about their relationship in her diary.
Lucy's intelligence in fanfiction can make her stand out as a powerful character. She can use her wits to strategize in battles. For instance, she might analyze her opponent's weaknesses quickly and then summon the most suitable spirit to counter them.