Well, perhaps Demon Naruto has some sort of special connection to Kushina that is related to his demonic powers. For example, her Uzumaki bloodline might be the key to controlling or understanding his demonic side better. And they could go on a journey to discover the secrets of his powers together.
In a fanfiction, it could be interesting if Demon Naruto was initially seen as a threat by Kushina, but as they interact more, she realizes that he is not all bad. They could then form an alliance to protect the Hidden Leaf Village from both internal and external threats. Maybe there's a prophecy about them working together to bring a new era of peace to the ninja world, but they have to overcome many obstacles, including the fear and distrust of the other villagers towards Demon Naruto.
A possible plot could be that there is a prophecy about Demon Naruto and Kushina. They have to work together to fulfill this prophecy which involves saving the ninja world from a great disaster. Along the way, they face many challenges. Kushina helps Naruto come to terms with his demon side, and Naruto uses his power to protect Kushina from the various threats they encounter. Their relationship evolves as they struggle to complete their task.
A third plot idea is a crossover where Kushina enters a world that combines Naruto elements with elements from a post - apocalyptic setting. She has to use her ninja skills to survive in this harsh new world. Maybe there are new types of chakra - based threats or she has to find a way to restore order using her leadership skills. This would put her in a completely different situation compared to what she's used to in the normal Naruto world and force her to adapt and grow in new ways.
One idea could be exploring Kushina's life before Naruto was born in more detail. Maybe show her training as a jinchuriki and how she met Minato. Another could be a story where Naruto discovers a hidden journal of Kushina's that reveals family secrets and advice for him.
Another plot could be a 'what - if' scenario. What if Kushina didn't die? Naruto grows up with his mother around. The story could explore how Kushina helps Naruto train, not just in ninjutsu but also in understanding his Uzumaki heritage. It could also show how their relationship affects Naruto's relationships with others in the village, like how he might be more confident with Kushina's support.
Well, a really interesting plot could be a fanfiction where Mikoto and Kushina's spirits are somehow able to communicate with Naruto at crucial moments in his life. They give him advice and strength, even though they are no longer alive. Also, a story about how they worked together to try and bridge the gap between the Uchiha and the rest of the village would be fascinating. They could use their influence and relationships to bring about positive change. This would involve a lot of character development for both of them and would show their importance in the Naruto world beyond just being Naruto's mother and a friend's mother.
One idea could be that the evil Naruto tries to manipulate Kushina's power for his own dark purposes. Maybe he wants to take over the Hidden Leaf Village using her influence as his mother. Another could be that he forms an alliance with the village's enemies, and Kushina has to make the tough choice between stopping her son or trying to save him from his evil ways.
One idea could be exploring Kushina's life before Naruto was born in more detail. Maybe show her training as a Jinchuriki and how she met Minato. Another could be a story where Naruto gets to time - travel and meets his mother when she was his age. It would be a great chance to see their relationship develop in a different way.
Well, a plot could be that Kushina is a reincarnated goddess. She doesn't know it at first, but she starts having strange dreams and premonitions. As she discovers her true nature, she has to learn how to use her goddess - like abilities, which include things like super - speed and the power to heal any wound. She then uses these powers to fight against a new and powerful enemy that threatens the ninja world.
Perhaps they are living in a parallel universe where everything is dark and gloomy. Dark Naruto and Dark Kushina could be trying to find a way to break through to the normal universe. They might encounter strange versions of their friends and foes, and have to battle their own inner demons along the way. For example, Dark Naruto might struggle with the darker aspects of the Nine - Tails' power that he has fully embraced in this universe.
One interesting plot could be that 'dark kushina' initially tries to manipulate Naruto for her own goals but gradually develops real feelings for him as she gets to know him better. Another could be that they are forced to work together to save the Hidden Leaf Village from a powerful enemy.