Naruto might initially be confused. He has grown up with a certain view of himself, and this new information about his heritage completely shatters that. He may struggle with his identity for a while, but as he digests the information, he could start to feel a sense of pride. He might think that now he has a greater purpose, something that ties him more closely to his family and the ninja world in general. He may also become more confident in his abilities, knowing that he comes from a great lineage.
Sakura might be shocked at first, but then she'd be really happy for Naruto. She'd probably be more protective of him too, especially if there are any threats related to his heritage. After all, she's always cared about him in her own way.
Well, Naruto could have a range of reactions. On one hand, he might feel a sense of isolation, thinking that he's different from all the other ninjas he knows. But on the other hand, his adventurous spirit could also make him curious about what this new part of him means. He might start to wonder about his powers and how they relate to his demon heritage. He could also be a bit scared, especially if he has been taught to fear demons in the ninja world.
He might feel angry and frustrated. Naruto has always been proud of his potential and his roots in some way. Being denied his heritage would be like taking away a part of his identity, so he'd likely be quite mad at those who are doing the denying.
Naruto's reaction could be complex. On one hand, he would be happy to find someone else from his clan. He has always been proud of his Uzumaki heritage despite not knowing much about it at first. But on the other hand, he might be a bit cautious. Karin has been associated with some not - so - good groups in the past. However, overall, his positive nature would probably lead him to approach Karin with an open mind and try to build a connection with her based on their shared Uzumaki roots.
He might be initially very confused and hurt. Naruto has always longed for a connection to his parents, and finding out they gave away his birthright could make him feel like he was unwanted or that they didn't trust him with it. He could go through a period of self - doubt, wondering if he is really worthy of being their son.
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.
Often, in these fanfictions, Naruto finding out about his heritage means uncovering secrets about his parents that were previously unknown. He could learn about their true motives, their relationships with other powerful characters, and how they influenced the events that led to his current situation. This knowledge might give him a new perspective on his life and his goals, and also create new conflicts and alliances as he tries to navigate the ninja world with this new information.
In many fanfictions, Naruto's reaction is a mix of shock and determination. The shock comes from finally learning about his clan, and the determination is to uphold the Uzumaki name. He could start wearing something that represents the Uzumaki clan, like a symbol on his clothing. He also may become more protective of the Uzumaki secrets and legacies he discovers.
At first, Naruto might be a bit hesitant. He's not used to having something so personal from his parents. But then, his curiosity would get the better of him, and he would slowly unroll the scrolls, his hands trembling slightly as he realizes that he's about to learn things he has always dreamed of knowing about his parents.
He would be very angry. Naruto is not one to take betrayal lightly.