Well, he might start with intense training sessions. Maybe he observes Kakashi closely for the Chidori, and for the Rasengan, he practices over and over again, gradually getting the hang of the chakra control required.
In a more creative fanfic, an ancient ninja who was the originator of the Chidori technique could appear. This ninja could be brought back to life through some sort of magic or jutsu. He sees Naruto's pure heart and decides to pass on the Chidori knowledge to him, believing Naruto will use it for good.
Sure, there are jutsus aplenty in the Naruto manga. They range from elemental jutsus like Fire Release and Water Release to powerful sealing techniques. These jutsus play a crucial role in shaping the battles and character development within the manga.
Maybe Sasuke teaches him the Chidori in a moment of camaraderie. And for the Rasengan, it could be an older and wiser Naruto from the future who travels back in time to teach his younger self.
In a fanfic where Naruto knows the Chidori, it could change the power dynamics in battles significantly. Naruto's already vast chakra reserves combined with the piercing and fast - acting nature of the Chidori would make him an even more formidable opponent. He could use it in close - quarter combat situations, perhaps integrating it with his Shadow Clone Jutsu in creative ways. For example, he could have clones perform the Chidori from different angles, catching his enemies off - guard.
In fanfiction, Naruto creating Chidori could be possible through some creative plot devices. Maybe he was taught by Sasuke in an alternate universe where they teamed up earlier. Or perhaps he discovered a scroll that had the knowledge of Chidori and was able to learn it on his own with his determination and quick - learning ability.
In many Naruto fanfictions, the Chidori - Rasengan combo is often portrayed as an extremely powerful and unique move. It combines the piercing nature of the Chidori with the rotational and explosive force of the Rasengan. Some fanfictions might have Naruto or Sasuke (or both in some cases) creating this combo during a crucial battle against a powerful enemy, like a new Akatsuki member or a rogue ninja from another village. This combo is usually described in great detail, with the lightning - chakra of the Chidori surrounding and enhancing the Rasengan, making it not only more destructive but also having an added effect like paralysis due to the electricity.
In Naruto fanfiction, forbidden jutsus often include things like the Edo Tensei in a more extreme or modified form. However, it's important to note that adult fanfiction may contain inappropriate or non - canon elements that deviate from the original Naruto story. So, it's better to focus on the official Naruto lore for a more accurate understanding of jutsus.
A really interesting secret jutsu in Naruto fanfic could be the 'Energy Absorption Jutsu'. This jutsu enables the user to absorb any form of energy, whether it's chakra - based attacks or natural energy from the surroundings. It gives the user a huge advantage in battle as they can then use the absorbed energy to power up their own attacks. There might also be a 'Teleportation Gate Jutsu' which creates multiple gates in different locations that the user can instantly teleport between. And the 'Aura Manipulation Jutsu' where the user can manipulate their own chakra aura to have different effects, like creating a shield or enhancing their physical abilities.