The origin of Naruto's starfire powers in fanfiction might be due to an experiment. Some rogue ninja or a secret organization could have been conducting experiments with celestial energy. Naruto somehow gets caught in one of these experiments and as a result, he gains the starfire powers. Another possibility is that it's a gift from the stars themselves. Naruto has always been a special character, and the stars, seeing his potential and pure heart, decide to grant him these powers to help him on his journey.
In some fanfictions, the chaos powers might come from an encounter with a powerful and mysterious entity. This entity could have bestowed these powers upon Naruto, either as a gift or as part of a greater plan. For example, a powerful spirit from an ancient realm might have seen Naruto's potential and decided to give him these chaos powers to help him in his journey.
Well, Naruto's Rasengan could be combined with Starfire's starbolts. For example, Naruto could use his chakra control to shape Starfire's energy into a Rasengan - like attack.
One possible origin could be a long - lost kekkei genkai. Maybe Naruto's family had a secret bloodline ability that was suppressed for generations, and now it resurfaces as the red chakra.
It could be due to a unique training method. In fanfiction, perhaps Naruto discovered a new way to purify his chakra through intense meditation or some sort of elemental training that no one else has tried before.
One possible origin could be a secret scroll he finds. Maybe it was hidden by an ancient shinobi who had the power to summon ravens, and Naruto stumbles upon it during one of his adventures.
In fanfiction, the chained blades could have various origins. One possibility is that they are a family heirloom that Naruto discovers. Maybe they were passed down from an unknown branch of his family. Another idea is that he finds them during a mission in some ancient ruins. The blades could be tied to a long - forgotten ninja clan that once had great power.
One possible origin could be a new type of training he undertakes. Maybe he discovers a hidden scroll that teaches him a unique form of physical conditioning that gives him super strength.
It could be a result of some kind of rare genetic mutation. Maybe there was a dormant gene in his Uzumaki bloodline that got activated under certain circumstances, like during a near - death experience or a powerful chakra surge.
In some fanfictions, it could be due to a genetic mutation or an unexpected side - effect of a jutsu he uses. For example, if he experiments with a new form of chakra manipulation, it might accidentally give him the power to summon swords. Or maybe it's a gift from the Sage of Six Paths in a different interpretation of the Naruto universe.
He could have the power of instant regeneration. So, no matter how severe the injury, Naruto could heal himself in a split second. This would make him extremely difficult to defeat in combat.