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.
It could have a big impact. Naruto might become more stable emotionally with Kushina around. This new - found stability could change how he approaches his rivalry with Sasuke. Instead of just chasing Sasuke out of a sense of comradeship and competition, he might do it also to show Kushina that he's a great shinobi. And Sasuke might also view Naruto differently, seeing him as someone with a complete family now, which could add new layers to their complex relationship.
Naruto would gain more confidence. With Kushina by his side, teaching him and giving him support, he would feel more secure in his abilities. He would know that he has his mother, a strong ninja in her own right, guiding him.
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.
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.
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.
If Kushina were alive in Naruto fanfiction, it could change the story in many ways. For one, Naruto would grow up with a mother figure. He might not have faced so much loneliness and discrimination in the village as Kushina could have protected him. Also, Kushina was a powerful kunoichi. She could have trained Naruto herself, perhaps passing on unique Uzumaki techniques earlier. This could have made Naruto even stronger, more quickly.
If Kushina was alive in a fanfiction, Naruto's relationship with his father, Minato, would be different. They could all be a proper family, and Naruto would grow up with both his parents. His relationship with his friends might also change as he would have a more stable home life. For example, he might be more confident around Sakura and Sasuke, and his bond with them could be less about seeking acceptance due to his lack of family.
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.
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.
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 common plot is Kushina finding Naruto in a different time or dimension. For example, she might end up in the future where Naruto has grown up and she gets to see the kind of person he has become. It's an emotional and interesting concept as she gets to witness all his achievements and the challenges he has overcome.