Maybe they enlist the help of other powerful ninjas. For instance, they could ask Tsunade for medical support in case Naruto is injured. They could also get intel from Shikamaru, who is known for his intelligence. By gathering a team of reliable and strong ninjas, they increase their chances of getting Naruto back successfully.
She might start by using her knowledge of Naruto's past. Since she is his mother, she knows things about his early life that no one else does. She could use these memories to create an emotional connection with him. Maybe she'll show up in his dreams first, like a hazy memory, and then gradually reveal herself in the real world.
Well, in some fanfictions, Minato might use his powerful jutsu to break through the barriers between the living and the dead and directly reach Naruto. He could also try to influence the people around Naruto to bring him closer to where Minato is, like using his spirit to communicate with Naruto's friends and convince them to help.
One possible plot could be that Minato and Kushina are somehow brought back to life in a spiritual or semi - physical form. They then embark on a journey through the ninja world to find Naruto. Along the way, they encounter various characters who either help or hinder them. Maybe they have to face some old enemies who are still lurking in the shadows and trying to stop them from reuniting with Naruto.
One way it could happen is if Naruto somehow gains the ability to travel back in time. Maybe through a powerful jutsu or a unique kekkei genkai. He could then use his knowledge of future events and his combat skills to save his parents from their tragic fate.
It might be due to jealousy. If Minato was getting more attention or praise in the village for his achievements while Kushina felt overlooked, that could create resentment. Say, Minato was constantly being hailed as a hero for his speed and battle tactics, and Kushina, who also had great power, felt like she was in his shadow.
In many Naruto fanfictions, Minato is often portrayed as an even more brilliant strategist and a loving husband. He might be shown using his Hiraishin no Jutsu in creative ways to protect Kushina. For example, in some stories, he uses it to surprise her with little gifts or to show up just in time when she's in danger.
In such a fanfiction scenario, the village of Konoha would be affected too. Minato is a respected figure. His abandonment could cause a scandal. Naruto might not have the same level of protection from the village elders. This could lead to different power dynamics within the village. Maybe other ninja clans would try to take advantage of Naruto's situation. Also, Kushina's family might react in various ways, some might try to find Minato and some might focus on taking care of Kushina and Naruto.
At first, Naruto and Kushina might start to distance themselves from Minato. They could avoid him and not talk to him as much. As time goes on, the hatred might grow deeper. Naruto could start to oppose Minato in public or in important village matters. Kushina might also try to influence others in the village against Minato.
Perhaps the fanfic could end with a more bittersweet note. Minato and Kushina are able to stop the immediate abuse, but they realize they can't always be there to protect Naruto. So they pass on their strength and values to Naruto in a more profound way, and he grows up determined to never let anyone be abused like he was.
If Kushina leaves Minato for Naruto in fanfiction, it would completely change the Naruto universe's family dynamics. Naruto might grow up with a different kind of support system. Instead of the absent father figure of Minato, he could have a more present mother figure in Kushina. This could also change his relationship with the village. Since Kushina was an Uzumaki, her presence could lead to Naruto having an earlier understanding of his heritage.