Obviously, Naruto is the central character. But there are also often other characters like Jiraiya. Since Jiraiya was Naruto's mentor in the original story and had knowledge about sage mode, he often appears in fanfics to guide Naruto in his training. Another common character could be Kakashi. He may offer some advice or support to Naruto during the training process.
In certain 'naruto sage training fanfic', there could be a plot where Naruto's sage training is intertwined with a prophecy. He has to train in a specific way to fulfill the prophecy and save the ninja world. This could lead to him having to master skills and powers that are far beyond what he originally thought possible during his sage training journey.
One interesting plot could be Naruto exploring new and unique sage training methods that are not in the original story. For example, he might discover a hidden sage realm with different rules and challenges.
Jiraiya is often a common character. Since he was Naruto's teacher and had knowledge of sage training himself, he might appear in the fanfiction to guide Naruto further. Another one could be Kakashi. He is always looking out for Naruto and could be involved in the training in some way, like providing strategic advice.
No. Slavery is an inhumane and immoral concept, and applying it to fanfiction characters from a series like Naruto, which has positive values, is completely inappropriate.
I'm not entirely sure as it's a rather specific and perhaps not so common fanfiction concept. It might be about Harry from the Harry Potter series being related in some strange way to Naruto's'splitting' concept, like a clone or some other form of division. But without reading it, it's hard to say for sure.
I'm not sure specifically as this is a rather unethical and inappropriate concept for fanfiction. In the Naruto universe, Hinata and Naruto have a relationship based on mutual respect and admiration, not slavery.
I'm not aware of the popularity of this specific fanfic. There are so many Naruto fanfics out there that it's hard to say whether this one has gained a large following.
Well, it could be that Minato is somehow transformed into an animal and Naruto finds him. Naruto, being kind - hearted, takes him in as a pet. And then there could be all sorts of adventures as Naruto tries to figure out how to turn Minato back, while also dealing with the normal Naruto - world problems like fighting bad guys and training.
I'm not sure of a specific 'minato is narutos pet' fanfiction off the top of my head. However, you can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. They have a vast collection of Naruto - related fanfictions, and you might be able to find one with such an interesting premise there.