Naruto is devastated. He feels a huge void in his heart. Jiraiya was the one who believed in him from the start, and his death makes Naruto question a lot of things. He might even start to doubt his own strength for a while.
In Naruto future reaction fanfiction, characters might react to various things. For example, they could react to new jutsu developed in the future. They might be amazed at the power and creativity behind it. Maybe Naruto himself would be excited to see how the next generation has advanced the art of ninjutsu.
In fanfiction, Sasuke's realization of Sakura's pregnancy can be filled with drama. He might question his own ability to be a father. However, his love for Sakura would drive him to overcome his doubts. He could start learning about pregnancy and child - rearing, and his relationship with Sakura would become more affectionate and caring as they anticipate the arrival of their baby.
Naruto would probably be deeply hurt. He values his relationship with Sasuke so much that such a betrayal would shatter him. He might become withdrawn or angry.
He might meet the future versions of Naruto and Sakura. Their relationship with him could be very different in the future, perhaps they are now leaders of the village and Sasuke has to adjust to their new status.
A frequent theme is the exploration of character relationships in the future. For instance, how do Naruto and Sasuke's relationship evolve further? And how do other characters react to this? Also, the theme of facing new, more powerful threats together often appears. Characters' reactions to these threats can vary from determination to fear.
He might be really surprised. He would see all kinds of new interpretations of his world, his friends, and his adventures. Some fanfics could show him achieving even greater things in the future, which would make him feel proud. And if there are fanfics that explore his relationships in new ways, he'd be quite intrigued.
Sasuke might be initially surprised. He is used to the Sakura from his past, so seeing a different, more mature future Sakura could catch him off guard.
Jiraiya's comfort gives Naruto the confidence to face his fears. For example, if Naruto was crying because he was afraid of a powerful enemy, Jiraiya's words of wisdom and support would make him more determined to train harder and find a way to defeat that enemy in the future.
If Sasuke watches Sakura kiss in a fanfic, his reaction could vary greatly. Given his stoic nature, he might try to hide his true feelings. However, deep down, he may feel a sense of betrayal even though it's just a fan - created story. It could also make him re - evaluate his own feelings for Sakura. Maybe he would start to realize that he has stronger feelings for her than he previously thought, or it could push him further away if he doesn't like what he sees.