She would likely be devastated. Kushina has a deep connection to Naruto as his mother. She might first go into denial, unable to accept that her son is gone. Then, she would probably be filled with intense grief and anger. She could potentially lash out at those she blames for his death or just break down completely, mourning all the things Naruto could have been and all the time they missed when he was growing up.
The village of Konoha would be in mourning. Naruto was a hero to them. Kushina's grief could spread throughout the village, dampening the spirits of everyone. There might be a sense of hopelessness as Naruto was often seen as the one to bring hope in difficult times.
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 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.
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 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.
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.
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.
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.
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.