Another possibility is that it has something to do with Naruto's Uzumaki heritage. There could be some latent power within his bloodline that gets awakened in a particular situation, like when he is in a life - or - death battle or in a place filled with strong chakra. This awakened power gives him the form of a dragon.
Well, in some fanfictions, it could be due to a special encounter. Maybe he meets a powerful dragon spirit during one of his adventures. This spirit, seeing Naruto's potential and kind heart, bestows upon him the power to transform into a dragon.
😋I recommend the book One Piece: Caesar to you. The protagonist's soul transmigrated to the pirate world and became Caesar Kurang. He had the ability of two fruits and transformed into a dragon. The protagonist would also know the future timeline of Luffy defeating Kaido. The keywords were One Piece, Caesar, Dragon, Twin Fruits, Hegemony, and so on. I hope you like my recommendation.😗
In fanfiction, a common way for a human to transform into a dragon is through a magical spell. Maybe an ancient wizard or a powerful magical artifact bestows this transformation ability on the human. For example, finding a magic amulet that, when activated, starts the transformation process gradually, with the human's body first tingling and then slowly taking on dragon - like features such as scales growing on the skin, the eyes changing shape and color, and wings sprouting from the back.
Maybe he discovers a hidden jutsu or ancient power source that has the ability to transform him into a dragon. It could be something that was left behind by an ancient clan or a long - forgotten ninja. As Naruto is always exploring and trying to become stronger, he stumbles upon this power and it changes him into a dragon.
Maybe Naruto discovers a hidden kekkei genkai within himself that allows him to transform into elements. This could be a result of some long - forgotten bloodline connection. He might first accidentally tap into this power during a life - threatening battle and then gradually learn to control it with the help of his friends and mentors.
Maybe they are caught in a magical experiment gone wrong. The experiment was aimed at creating artificial dragon slayers, and Lucy and Levy end up being the accidental subjects. Their existing magic gets combined with dragon - slaying magic. Lucy's celestial spirits might be enhanced with dragon - slayer - like traits, and Levy's script magic could start to incorporate dragon runes that give her the power to harm dragons. They then have to figure out how to control these new and unexpected powers while on their journey to become full - fledged dragon slayers.
It could strengthen their relationship. If Naruto's transformation is a sign of his growth and power, Sakura might see him in a new light. She could start to rely on him more and respect him even more as a ninja. This newfound respect could lead to a closer friendship or even the start of something more romantic, depending on how the story is written.
In some fanfictions, Natsu might gain the ability to use Dragon Force through intense training. He could be pushed to his limits by a powerful opponent or a difficult situation, forcing his body and magic to adapt and unlock this powerful form.
Well, in Naruto fanfiction, the idea of transformation and clone jutsus can be used in really creative ways. However, the 'lemon' aspect often refers to more adult - themed or romantic situations. But if we consider how they might be connected, perhaps a character could use a transformation or clone jutsu to get closer to a love interest in a 'lemon' - esque scenario. For example, a clone could be used to spy on a potential partner's true feelings, and then the character could transform to be more appealing when they finally reveal themselves.
In some really creative fanfictions, Naruto could transform into more exotic elements. He might be able to turn into a plasma - like state, with all the heat and energy that comes with it. Or perhaps he could transform into aether, a more spiritual and intangible element that gives him unique abilities like phasing through objects or teleporting short distances.
In some fanfictions, it could be due to a new jutsu he discovers. Maybe during a secret training session in an ancient scroll, he finds a forbidden technique that allows him to control people.