One possibility could be that Naruto, for some reason, joins the League of Legends world and then betrays the other champions. Maybe he's been influenced by an evil force. For example, he could be tricked into believing that the League is actually a threat to his own world of Naruto, so he turns against them.
Perhaps Naruto is initially excited to be in the League of Legends world. He forms alliances with some of the champions. But then, he discovers a dark secret about the League, like they are using power in a corrupt way. Feeling deceived, he decides to betray the League. He could then start his own rebellion within the League, using his unique abilities like shadow clones and rasengan to fight against the champions who still support the League's old ways.
Well, in a fanfiction like this, it might be that Naruto is brought into the League of Legends universe against his will. He tries to find a way back to his own world but is constantly thwarted by the League's rules and regulations. This could lead him to feel betrayed by the League, and in turn, he betrays them. He might use his ninja skills in unexpected ways that the League champions are not prepared for.
Well, one possibility could be that the Justice League misinterprets Naruto's powers as a threat. Maybe they see his shadow clone jutsu as some form of dangerous cloning that could disrupt the balance in their world. So, they turn on him without really understanding his true intentions.
Perhaps there's a prophecy in both worlds that Naruto and Jinx are the ones who can prevent a great disaster. They initially don't believe it but as strange events start to occur, they are forced to work together. Jinx's explosive devices could be combined with Naruto's Rasengan in some creative ways to defeat the approaching doom. Their relationship could be full of bickering at first, but as they face challenges, they start to respect and rely on each other.
Naruto's ability to tap into the Nine - Tails' chakra would be a game - changer. In a betrayal scenario, if he's pushed to his limits, he could unleash the power of the Nine - Tails. This would make him extremely powerful, perhaps even on a level that the League of Legends champions have never faced before. He could use this power to fight against the League, causing massive destruction and upheaval in the League's world.
The fanfiction might revolve around a team in League of Legends. One of the members experiences a loss of mind because of a personal tragedy off - the - field. This could be something like the loss of a loved one or betrayal by someone they trusted. Their mental state then affects their performance in the game and the overall dynamics of the team.
In this fanfiction, it might be that Sirzechs is being manipulated by some dark force. This dark force convinces Sirzechs that Naruto is evil. As a result, Sirzechs betrays Naruto. Naruto then has to not only deal with the betrayal but also figure out how to stop this dark force that is causing so much chaos and misunderstanding.
Perhaps in this fanfiction, Yugao is secretly working for a hidden organization that wants to get rid of Naruto. She betrays him by revealing his secrets or setting him up in dangerous situations. Naruto, being the kind - hearted person he is, initially doesn't want to believe she would do such a thing and tries to reason with her, but she is too far gone in her loyalty to the other side.
In this fanfiction, perhaps there's a power struggle. Naruto, being a powerful ninja, could be seen as a threat to the RWBY world's power balance. So, the RWBY characters, out of fear or a sense of self - preservation, betray him. They might think he'll disrupt their way of life or take over their territory.
One possible plot could be that Jiraiya is forced to betray Naruto due to some external threat. Maybe an enemy has captured Jiraiya's loved ones and threatened to kill them if he doesn't turn on Naruto. Jiraiya, in a difficult position, might have to pretend to be against Naruto to protect his loved ones while secretly trying to find a way to free both Naruto and his family from the enemy's clutches.
Well, one possibility could be that Mavis has some sort of hidden agenda. Maybe she's being controlled by a greater evil force that makes her turn on Naruto. It could also be a misunderstanding. For example, false information is spread about Naruto, and Mavis believes it without proper investigation. Another idea is that Mavis has a different view of the ninja world compared to Naruto, and their conflicting ideologies lead to her betraying him.
Well, it could be that Kurenai is somehow deceived into believing Naruto has done something really bad. Maybe she's tricked by an enemy who fakes evidence against Naruto. So, in her misunderstanding, she turns against him.