Perhaps in the fanfiction, the Quidditch team gets influenced by a dark wizard who has a grudge against Harry. The wizard uses a spell to make the team members believe Harry is a threat to them. So they start to betray him by not passing the Quaffle to him during the game, or even colliding with him on purpose during a fly - around. This would lead to Harry feeling extremely isolated and confused as he thought his team was like family.
In this kind of fanfiction, it could be that there's a prophecy related to Harry in the Quidditch context. Some team members, fearing the implications of the prophecy, decide to betray Harry. For example, if the prophecy says that Harry will bring great change to the Quidditch world but some players are afraid of change. They might start by excluding Harry from team practices, then gradually make him an outcast in the team. Harry would then have to fight not only his external enemies in the Quidditch matches but also the betrayal from within his own team.
It could be a new player on the team who is jealous of Harry's skills and popularity. This new player might spread lies about Harry, turning the other team members against him. So the new player would be the main antagonist in this scenario.
Well, the story might start with Harry getting an unexpected invitation to join a professional Quidditch team. He has to quickly adapt to the more competitive and cut - throat environment. His old Hogwarts friends might be jealous or proud. As he progresses in the team, he could be involved in a big tournament where the fate of the team depends on his performance.
In this fanfiction, Harry might face intense training sessions. He could struggle at first to keep up with the more experienced players on the team. Maybe he'll have a rival on the team who doubts his abilities but he'll prove them wrong with his natural talent.
One great fanfiction is 'The Gryffindor Quidditch Revolution'. It focuses on a new player who brings innovative strategies to the team. The story is full of action - the intense Quidditch matches are described vividly, making you feel like you're right there in the stands. The characters are well - developed, and it stays true to the spirit of the Gryffindor team in the original books.
Well, perhaps in this fanfic, Harry could be wrongly accused of a serious crime like dark magic use. Everyone, including his friends Hermione and Ron, might turn their backs on him due to false evidence. He would then have to fight alone to clear his name and find out who really framed him.
In a 'Harry Potter betrayed by Gryffindor' fanfiction, perhaps there is a prophecy that is misinterpreted. The Gryffindors think Harry is the cause of upcoming doom instead of the savior. So, they begin to betray him. Harry would then have to struggle not only with the external dark forces but also with the internal pain of being rejected by those he considered friends and housemates. He might start to question his own identity and values, and his journey would be about regaining the trust of Gryffindor or finding his own path without them.
One possible reason could be jealousy. Maybe Harry has some extraordinary talent that makes the other team members feel threatened. For example, if he's a much better flyer or has a special ability related to the game that they don't. Another reason might be some false rumors spread about him. If someone starts a rumor that Harry is using unfair means to win, like a made - up magic charm, the team might shun him out of a sense of fairness in the game.
One possible plot could be that Team 7 is manipulated by a powerful enemy. Maybe Orochimaru manages to cast a powerful genjutsu on them, making them believe Naruto has turned evil. So they turn against him. It could also be that they are forced to choose between Naruto and the safety of the village in some extreme situation and they wrongly choose to sacrifice Naruto.
The sense of adventure. In the original books, the Gryffindor Quidditch team was always at the center of exciting action. Fanfictions build on this. They take the team on new adventures, like facing never - before - seen opponents or dealing with magical mishaps during a match. It's like getting to experience more of the wizarding world through the lens of the team we all love.
In this fanfiction, it might be that a misunderstanding is at the core. The village elders could spread false rumors about Naruto having some sort of dark power. Team 7, believing these rumors, decides to side against Naruto. Haku, who has his own motives related to the power struggle in the ninja world, takes advantage of the situation. He could manipulate Team 7 into thinking Naruto is a danger and needs to be stopped, which would be a heartbreaking betrayal for Naruto.