Perhaps in the fanfiction, Kushina is summoned from the afterlife. She has some unfinished business which is to protect her son, Naruto. When Naruto is about to be overwhelmed by a horde of rogue ninjas, Kushina's spirit emerges. She uses her strong willpower which is translated into a kind of spiritual energy to shield Naruto and then guides him to defeat the enemies.
In one possibility, Kushina could use her chakra chains to fend off attackers. Since she was a powerful kunoichi, she might sense Naruto in danger and appear in a moment of need. Maybe Naruto is facing a powerful enemy like Pain, and Kushina's sudden arrival and her unique abilities turn the tide of the battle, saving Naruto from certain death.
Maybe the plot is centered around Kushina's relationships. She gets to meet her son Naruto as an adult and is proud of the man he has become. She also reconnects with old friends and allies. But then, there are those who are not happy about her return, fearing that she might disrupt the current power balance in the village, and Naruto has to defend her.
One possibility could be that Naruto discovers a long - hidden secret about his family that makes him feel betrayed. For example, he might find out that Minato and Kushina had made a deal with a dangerous enemy in the past that put the village at risk. This would be so against Naruto's values of protecting the village and his friends that he decides to leave them.
Maybe in the fanfiction, there is a powerful enemy who wants to use Naruto's connection to his parents against him. So, they somehow manage to bring Minato and Kushina back to the physical world. When they meet Naruto, it's an emotional moment. They form a plan to defeat the enemy together. Minato uses his strategic skills, Kushina her strength, and Naruto his own unique abilities learned over the years.
One possible plot could be that they have to face challenges together in a post - war Konoha. They might work on rebuilding the village while also dealing with their new family life. Naruto, with his experience and Kushina's strong will, could make a great team in leading the village in a new direction.
In this fanfiction, the plot might involve Kushina coming back to help Naruto in his toughest battles. Maybe she uses her unique chakra abilities that Naruto has inherited to give him an edge. She could also provide emotional support, as Naruto has always longed for his mother.
One possible plot could be that Naruto somehow inherits the Rinnegan from an unexpected source and Kushina, being his mother, helps him understand and control this new power. Maybe they discover a hidden connection between the Uzumaki clan and the Rinnegan's origin, leading them on a journey to uncover secrets long lost in the ninja world.
One possible plot could be that Naruto, with his powerful jutsu and leadership skills, takes charge in a situation where Kushina's safety is at stake. He might use his Rasengan to fend off enemies and dominate the battlefield, protecting his mother Kushina in the process.
One possible plot could be that Kushina's departure makes Naruto more determined to prove himself. He might strive harder in his ninja training, using the pain of his mother leaving as motivation. This could lead to him achieving new levels of power at a faster rate.
Perhaps there's a time - travel element involved. Naruto from the future, who has been through some horrible experiences, travels back in time and, in a state of confusion or rage, attacks Kushina. Or it could be that a powerful villain has the ability to manipulate Naruto's emotions and uses that power to make him turn on his mother. This would create a very complex and dark plotline that challenges the normal Naruto narrative.
One possible plot could be that Naruto punishes Kushina for some misdeed she did in the alternate fanfiction universe. Maybe she made a decision that put the village in danger, and Naruto, as a hero, has to take action to set things right.