Well, one possibility is that Dark Naruto would be overjoyed. After all, Kushina is his mother. But at the same time, he could be very conflicted. His dark side might make him suspicious of her motives. He could test her in various ways to see if she's really who she says she is. And Kushina, on her part, would probably be heartbroken to see what her son has become.
Perhaps Dark Naruto would use this discovery as a chance for redemption. Knowing his mother is alive could be the spark that starts to lighten his dark side. He might start to remember the love she once had for him. Kushina could then try to guide him back to the right path, using their mother - son bond as a powerful tool. However, it won't be easy as Dark Naruto's dark experiences won't just disappear overnight.
One thing that could happen is that Dark Naruto would be filled with a mix of emotions. He could be angry at the village for hiding this from him, yet also feel a glimmer of hope. This discovery might make him question his loyalty to the forces that led him to become 'dark'. He might also feel a sense of longing for the family he thought he had lost.
She might be overjoyed. After all, Naruto is her son. She could immediately rush to find him and embrace him tightly, tears of happiness streaming down her face.
Well, one possibility is that Naruto would be overjoyed. He has always longed for his mother's love. He might spend days just talking to her, sharing all his experiences, from his training with Jiraiya to his battles against the Akatsuki. Kushina would probably be extremely proud of him and would start teaching him some Uzumaki clan jutsus that were passed down in the family. And Naruto's relationship with the village would also change. He would no longer be the orphan that everyone pitied. Instead, he would be the son of a hero, which could bring a whole new dynamic to his standing in Konoha.
One consequence could be a shift in the power dynamics. If Kushina is alive and now reunited with Naruto, they could form a powerful duo. This might make their enemies more cautious or even lead to new alliances being formed against them. Also, Naruto's morale would be greatly boosted, and he might become even more determined in his goals, which could speed up the overall plot development.
Naruto's personality could become more confident and stable. With a mother figure in his life, he would have someone to turn to for emotional support. He might not be as impulsive as he was before because Kushina could give him advice based on her own experiences. For example, when dealing with conflicts in the village or with other ninja, he would think twice instead of jumping into action right away.
One possible plot twist could be that Kushina's survival was part of a grand plan by an unknown entity. Maybe she was hidden away to protect Naruto from some greater threat that was yet to be revealed. Another aspect could be the emotional turmoil Naruto would go through. He'd be overjoyed, of course, but also confused and maybe a bit angry that he was made to believe she was dead all this time.
If Naruto found Kushina alive in a fanfiction, it might lessen his focus on Sasuke for a while. He'd be more centered on getting to know his mother. But in the long run, it could also make him stronger and more determined in his rivalry with Sasuke. With Kushina's support, Naruto would have a new source of motivation to prove himself not just to Sasuke, but also to his mother.
Well, Kushina could initially be disappointed. But then she might see it as an opportunity to help Naruto find his true passion. She could start introducing him to different things, like maybe some traditional Uzumaki family skills that don't necessarily involve being a ninja in the typical sense. This way, Naruto could still have a sense of purpose and connection to his heritage.
One possible fanfiction could be about Kushina finding Naruto in a situation where he's lost in a forest. Maybe she uses her unique chakra sensing abilities to track him down. It could be a heartwarming story of a mother reuniting with her son.
One great fanfic could be 'Naruto's Reunion with Kushina'. In this fanfic, Naruto discovers a hidden jutsu that allows him to travel back in time and he meets his mother Kushina. It's a heartwarming story as they bond and Kushina gets to see the amazing person Naruto has become.