One possible plotline could be that Naruto is somehow transported back in time and has to fight Kushina in a misunderstanding. Maybe he's mistaken for an enemy due to some time - warp magic or jutsu gone wrong. Another could be a scenario where Kushina is controlled by an evil force, and Naruto has to fight her to break the control. Or perhaps it's a sparring match in a dream world where Naruto and Kushina test each other's skills without real harm.
One possible plotline could be that Naruto discovers some long - lost secret about his mother Kushina and decides to leave the village with her to explore this mystery further. Maybe they are on a quest to find some hidden power or knowledge that is related to Kushina's Uzumaki heritage.
One possible plotline could be Naruto's struggle with abandonment issues. Since Kushina left, Naruto might have a harder time finding his place in the village. He could become more withdrawn and have to fight even harder to prove himself. Another could be the search for Kushina. Naruto might embark on a journey to find out why she left and try to bring her back.
In this fanfiction scenario, it could be set in an alternate universe where Hiruzen didn't die. Naruto, having grown powerful, might be in a conflict of ideologies with Hiruzen. Naruto, with his more modern and inclusive views, could clash with Hiruzen's more traditional ways. This leads to a fight where Naruto tries to prove his point through combat, using his new and improved jutsu that he developed through his own unique training methods.
One possible plotline could be that Kushina's survival changes Naruto's upbringing completely. Instead of being an orphan, he grows up with a loving mother. This could lead to him being more confident and less of an outcast in the village at a young age. He might also learn about the Uzumaki clan's secrets earlier from his mother, which could make him a more formidable ninja even faster.
One possible plotline could be Naruto growing up with a sense of deep abandonment and having to face the world alone. This could lead to him having a much more cynical view of life. He might struggle more with controlling the Kyuubi's power as he has no guidance from Kushina. Another aspect could be his relationships with other characters like Iruka or Sasuke being different. Without Kushina's love, he may be more desperate for any form of connection.
Another plotline could involve the Shinigami within Naruto having some sort of mission related to Kushina. The Shinigami might need Naruto to help Kushina fulfill an unfinished task. As Naruto and Kushina work together, they also get to bond on a deeper level, with Naruto learning more about his mother's past and her love for the village and his father.
There might be a very dark and twisted fanfiction like that. It could be that Naruto is tricked into believing that Minato and Kushina are some kind of threat to the village or to his friends. So in a moment of confusion and misinformation, he takes drastic action. But this goes completely against Naruto's character in the original series.
A plotline might involve Kushina being a 'psycho' due to some past trauma. This could lead to her having a hidden agenda within the Hidden Leaf Village. She could be secretly plotting against some of the village leaders while pretending to be a normal citizen. And Naruto, being her son, gets caught in the middle of her schemes and has to figure out how to deal with her and protect the village at the same time. It could also show how Naruto's friends react to this new, darker side of Kushina.
In this fanfic, it could be a fight in an alternate universe where Naruto and Hinata belong to rival clans. Their clans' long - standing feud forces them to fight each other. However, during the fight, they start to realize that the feud is baseless and they might even develop a new understanding of each other and their clans' history.
A plotline could be that Naruto has to keep his true parentage a secret for a long time. This secrecy adds to his internal conflict as he tries to fit in with the other ninjas. As the son of Kyuubi and Kushina, he may be hunted by certain groups who want to either use his power or destroy it. He then has to go on a quest to find out more about his parents and his own identity, all while fending off these threats.