Well, it could be for the sake of exploring a darker side of Naruto's character. Writers often like to take a well - known positive character and see what would happen if they were pushed to their limits. Losing someone he loves deeply or being betrayed could be the trigger.
Fanfiction writers might also want to create an alternate universe where Naruto's life takes a completely different turn. If certain events in his life were changed, like if Jiraiya didn't train him properly or if he was exposed to different ideologies from a young age, he could end up like Obito. For instance, if he grew up believing that power is the only thing that matters, similar to Obito's view after his fall, he would act accordingly.
If Naruto was raised by Obito, he would likely be more exposed to the Uchiha side of things. Obito could train Naruto to be a more stealthy and strategic fighter. Naruto might not have the same bond with Iruka or the other villagers as in the original. His goals might be more aligned with Obito's views on the ninja world, which could be either for better or for worse. It would definitely make for a very interesting and different Naruto than the one we know.
One way could be that Naruto experiences a great loss, similar to Obito losing Rin. This loss could make him question the ninja world and its values, leading him to take a darker path. For example, if he lost Hinata in a cruel way, it might shatter his positive view of the world.
Obito's influence would likely make Naruto more aware of the darker side of the ninja world. Naruto is usually very optimistic, but with Obito's guidance, he would see the hardships and betrayals that can happen. For example, Naruto might become more cautious in his trust of others.
In some fanfictions, Naruto might hate Obito because of Obito's actions in the main Naruto storyline. Obito was involved in many heinous acts like causing the Nine - Tails attack on Konoha which led to the death of many, including Naruto's parents. This could be a reason for Naruto's hatred in fan - made stories.
Well, it could lead to a really intense situation. Naruto's friends would surely start a massive search for him. Sasuke might be especially driven to find Naruto as their bond is strong. They would probably trace Obito's whereabouts through his unique chakra signature or any clues he left behind.
If Naruto is trained by Obito in fanfiction, it would be a wild ride. Obito has a lot of knowledge about the Sharingan and space - time ninjutsu. Naruto could potentially incorporate some of these elements into his own fighting style. This would make him even more unpredictable in battle. Also, Obito's experiences and his view of the world might rub off on Naruto, leading to some interesting character development.
Obito might be initially hesitant and a bit awkward around Baby Naruto. But as time passes, he could develop a soft spot for the baby. He might play simple games with Naruto like peek - a - boo or make funny faces to make him laugh.
Sakura would probably be very shocked at first. She might be worried about Naruto's well - being and also a bit fearful of the combined entity. Kakashi, on the other hand, would be more understanding. Given his connection to both Naruto and Obito, he would try to communicate with the merged form to figure out what happened. Sasuke would be initially suspicious, thinking it could be some new threat. But after seeing that Naruto's essence is still there, he might be more accepting and see it as a new power to use against their common enemies.
The impact would be huge. Naruto has always been a symbol of hope and friendship in the Naruto world. If he becomes like Obito, that symbol would be shattered. His friends and allies would be in shock and confusion. Konoha would likely be thrown into chaos as they try to figure out what happened to Naruto and how to deal with his new, potentially dangerous mindset.
The plot could be really interesting. Since Obito has been through so much, he might train Naruto in a more unorthodox way. Rin, on the other hand, would provide a more nurturing and moral compass for Naruto. They could also influence Naruto's relationships. He might not have the same bond with Sasuke or Sakura as in the original. Instead, he could form new alliances based on what he learned from Obito and Rin.