Well, it could be that Sonic accidentally ends up in the Hidden Leaf Village in the Naruto world. The ninja there are preoccupied with their training and missions. Sonic, with his super speed and different abilities, is an oddity. But instead of being welcomed, he's mostly neglected. He might try to join in on their activities, like the Chunin Exams, but is constantly overlooked. This could lead to a story where Sonic tries to find his place in this new world while also feeling the sting of being ignored.
Sonic would be a main character for sure. Then there could be other Naruto characters like Sasuke and Sakura. Sasuke might be so focused on his revenge and training that he doesn't give Sonic a second thought. Sakura could be too caught up in her medical ninjutsu studies and her feelings for Sasuke. So Sonic is left in a world where these important characters are basically ignoring him, which makes for an interesting dynamic.
The plot could involve Naruto finding himself in a situation where he has to interact with Rias's brother. The brother, being too involved in his own world of power and politics, simply brushes Naruto off as unimportant. Naruto then decides to prove himself not through grand displays of power, but through his kind heart. He helps those in Rias's group who are being overlooked or underestimated, just like he was in his own village. This catches the attention of Rias's brother who starts to see the value in Naruto he had previously neglected.
Well, one possible plot could be Naruto being transported to the Sonic world. He might initially be confused by the strange new environment filled with fast - paced creatures and loops. He could then team up with Sonic and his friends to fight a common enemy, like an evil wizard who wants to take over both the Naruto and Sonic universes. Using Naruto's ninja skills and Sonic's speed, they could create some really cool battle scenes.
In a 'naruto meets sonic fanfiction', it could be that there is a tournament where characters from different universes are invited to participate. Naruto and Sonic both enter. At first, they are rivals, but as they face tougher opponents in the tournament, they realize that they need to work together. They combine Sonic's speed and Naruto's strength and strategic thinking to win the tournament and in the process, they become friends and learn a lot about each other's worlds.
One possible plot could be that Naruto is somehow transported to the Sonic universe. He encounters Metal Sonic, who mistakes Naruto for a threat. Naruto, using his ninja skills, tries to communicate with Metal Sonic but fails. So, he has to use his combat abilities to defend himself against Metal Sonic's attacks while also trying to find a way back to his own world.
One possible plot could be that in a crossover world, Naruto is somehow neglected by his usual friends and allies. Meanwhile, a Yugioh character, perhaps Yugi, stumbles into this world. Yugi notices Naruto's situation and decides to use the power of the Millennium Puzzle to help Naruto regain his confidence and the respect of those around him. They form an unlikely friendship and together face challenges that the neglect has caused, like Naruto having to prove himself all over again in battles.
One possible plot could be that Sonic accidentally runs through a portal and ends up in the Naruto universe. He meets Naruto and his friends, and they initially mistake him for some kind of strange summon. Sonic's speed could be a great asset in battles against the Akatsuki. For example, he could quickly retrieve intel or rescue hostages. And Naruto could teach Sonic about the power of friendship and determination in a different way than he's used to in his own world.
It could be about Kurt being neglected by his friends or family for a night. Maybe they all go out and leave him behind, and he has to deal with his feelings of loneliness and abandonment during that time.
One possible plot could be that Sonic somehow gets transported to the Naruto universe. He teams up with Naruto to stop an evil force that is using both chaos emeralds and ninja jutsu to create chaos. Sonic's speed could be a great asset in the battles, and Naruto's determination and jutsu would also contribute a lot.
It could also be due to personal relationships. Perhaps some of his closest friends get caught up in their own lives. Like Sasuke might be on a long - term mission and not be there for Naruto, and Sakura might be too busy with her medical studies. So Naruto, who is used to having a support system, suddenly feels alone and neglected.