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.
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.
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.
He might be really angry at first. Natsu is a passionate character, and being kicked out unjustly would make him furious. He could storm off vowing to prove his worth and show the guild they made a mistake.
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.
There are some great ones. Some focus on Natsu's growth and how he overcomes final challenges at the end of the Fairy Tail story. Others might explore his relationships in a more in - depth way as the story comes to a close. It really depends on what kind of story you're interested in. If you like action - packed endings, look for ones where Natsu is using his full power to save the day. If you prefer more character - driven stories, there are those that deal with his emotions and bonds with other characters at the end.
One possible reason could be a misunderstanding. Maybe there was a miscommunication during a mission, and the other members of Team Natsu thought Lucy made a big mistake. For example, if she accidentally led the enemy to their hiding place. Another reason might be jealousy. If Lucy's celestial spirit magic started to gain too much attention and overshadowed the others in some way, they could have decided to kick her out. However, this is all just speculation based on the idea of this fanfiction scenario.
Yes, there are likely fanfictions with such a plot. Fanfiction often explores different scenarios and relationships within the 'Fairy Tail' universe. However, not all of them are well - written or in line with the original spirit of the series.
Natsu would likely be extremely hurt. He has always been loyal to Fairy Tail, so being betrayed would be a huge blow. He might initially be in disbelief, not wanting to accept that his friends and guildmates could turn on him.
Lucy might be heartbroken. After all, Team Natsu was like a family to her. She could initially go into a state of shock and disbelief. Maybe she would try to plead with the team to let her back in, explaining that whatever they thought she did was a misunderstanding.