If in the fanfiction everyone believes Naruto is dead, it would have a huge impact. Firstly, the balance of power in the ninja world would shift. Allies of Konoha might feel less secure. Secondly, the emotional toll on his loved ones would be immense. Hinata would be devastated, and she might struggle to raise Boruto alone. Thirdly, the story could take a turn where Naruto is actually alive but in a different dimension or held captive, and the fanfiction could then focus on the journey to bring him back.
The story might progress with his friends and family trying to come to terms with his 'death'. Some might go into seclusion, like Hinata maybe. Others could start investigations to find out what really happened.
Well, if Naruto thinks he's the Kyuubi in a fanfic, he would probably start to exhibit more of the Kyuubi's traits. He might become more aggressive and less patient. His appearance could also change, maybe having some Kyuubi - like features all the time. And his training would take a whole new turn, as he'd be trying to master the power he believes is his own, which is really the Kyuubi's.
In such a fanfiction, Naruto might find himself in a very lonely and confusing situation. He would have to relearn about his relationships and the world around him. Maybe he'd be more cautious as he doesn't remember who is friend or foe.
Well, in such a fanfiction, there could be a lot of drama. Maybe Sakura starts acting really love - struck towards Naruto, while Naruto is completely oblivious at first. This could lead to some really comical misunderstandings, like Sakura bringing Naruto lunch every day thinking it's a couple - thing, but Naruto just thinks it's a friendly gesture.
Well, if Naruto is godlike and betrayed by everyone in a fanfic, it could start with the villagers' fear of his newfound power. They might think he's a threat and turn on him. Naruto, being so powerful, could initially be in disbelief. But as the betrayal sinks in, he might decide to leave the Hidden Leaf. He could then wander the world, trying to figure out his place in it while also being cautious of those who might want to take advantage of his power or finish him off.
In such a fanfiction, the Hokage might be consumed by grief. They could vow to find out who was responsible for Naruto's death and seek revenge. It could also lead to a dark period in the Hidden Leaf Village, with the villagers losing hope as Naruto was seen as a symbol of strength and unity.
Well, in a fanfiction where everyone sees Naruto's memories, it would be a wild ride. For one, Naruto has so many memories related to his training with Jiraiya. These could inspire the younger generation of ninjas to train harder. His memories of the Akatsuki battles could give the ninja villages a better understanding of their enemies. Also, his personal memories of loss, like the death of his parents, could make the villagers more protective of him and more committed to the idea of peace in the ninja world.
In such a fanfic, Naruto might become extremely bitter. He could lose his positive attitude and turn against the village that once shunned him. Maybe he would seek power elsewhere, perhaps from darker sources.
In such a fanfiction, Naruto might develop a very different personality. He could be more chaotic and unpredictable like Joker. His moral compass might be a bit skewed, and he'd probably use unorthodox methods to achieve his goals. For example, instead of Naruto's usual straightforward and positive approach, he might play mind games with his opponents.
If Naruto had an IQ of 500 in this fanfiction, his social life would also change. He would be able to communicate more effectively with people from different backgrounds. He could understand the nuances of different cultures within the ninja world and use that knowledge to build stronger relationships. His leadership skills would soar as he could make well - informed decisions quickly. He could also use his intelligence to develop new forms of art and culture in the village, enriching the lives of his fellow villagers.