Jiraiya could still play a role. Even if Naruto is raising himself, Jiraiya might cross paths with him and see his potential. He could offer some sporadic guidance without fully taking Naruto under his wing.
One plot could be Naruto creating his own unique ninja style. Since he has to raise himself, he would be more creative in combat. He might combine different basic jutsu to form something entirely new, which would make him stand out even more in the ninja world.
In this fanfiction, Tony might be stranded on an unknown planet or in a different dimension. He has to use his wits and the little knowledge he has to not only survive but also better himself. He might start with basic survival skills like finding food and shelter, and then move on to more advanced self - improvement, such as enhancing his physical and mental abilities through self - training and self - experimentation.
Well, perhaps the plot could involve Harry having to fend for himself from a very young age in the wizarding world. He might have to figure out magic on his own, without much guidance from adults. Maybe he starts exploring the secrets of Hogwarts by himself earlier than in the original story, leading to all sorts of unexpected adventures.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can use the search function to look for 'Harry raises himself' specifically. Another option is Fanfiction.net, which also has a wide range of Harry Potter fanfictions.
One possible plot could be that Harry uses some powerful time - turning magic to go back in time. He then has to hide his true identity from his younger self while trying to guide and raise himself. Maybe he teaches his younger self some advanced magic that he didn't learn until later in his original life, like more complex Patronus charms or advanced defensive spells.
In this fanfiction scenario, Naruto raising Hanabi could bring about some interesting character developments. Naruto's positive and determined nature might inspire Hanabi to be more confident. He could teach her some of his ninja techniques, like the Rasengan in a modified form suitable for her. And perhaps he'd also share his values of friendship and never giving up, which would shape Hanabi into a more well - rounded and strong kunoichi.
One popular 'Harry raises himself' fanfiction could be 'Alone but Not Defeated'. In it, Harry uses his wits and the limited knowledge he has to grow up independently. Another might be 'Self - Raised Wizard' where he discovers magic on his own and starts to train himself secretly.
One possible antagonist could be the time itself. Since Harry is messing with the natural flow of time, there could be some sort of time - based magic or entity that tries to stop him. It might be a time - keeper or some ancient magic that protects the integrity of the timeline.
One possible reason could be the burden of his past. Naruto has faced a lot of hardships and the memories might be overwhelming him, making him want to be alone. For example, the loss of his master Jiraiya might have left a deep scar, and he might feel that isolating himself is the only way to deal with that pain.