Well, in the fanfiction where Naruto finds Kushina on Kaiju Island, it could lead to a whole new adventure. Naruto might initially be in shock, but then quickly embrace his mother. Kushina, being a strong ninja herself, could teach Naruto new jutsus or ways to enhance his chakra control. They could also encounter strange creatures on the island, and with their combined skills, either fight them off or find a way to co - exist. It would be a great opportunity for Naruto to bond with his mother and grow even stronger as a ninja.
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.
Their relationship would likely develop very quickly. Naruto would be so excited to have his mother back that he'd be very affectionate. Kushina would probably be protective of Naruto right away. They'd start sharing stories about their lives, and Naruto would listen intently to Kushina's tales of his father and the Uzumaki clan.
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.
You can try websites like Fanfiction.net or Archive of Our Own (AO3). On Fanfiction.net, you can simply search for 'Kushina finds Naruto' in the search bar and it will show you a list of relevant fanfictions. AO3 also has a large collection, and their tagging system can help you narrow down your search to find exactly what you're looking for.
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, 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 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 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.
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.