One possible plotline could be that Naruto discovers a new jutsu that not only enhances his power but also changes his appearance. This jutsu might have some unforeseen side effects that gradually make him more and more handsome. For example, it could be related to chakra control and as he masters it better, his physical features start to change in a more appealing way. Maybe his hair becomes shinier, his eyes more piercing, and his face more chiseled.
In a fanfic, Naruto could be sent on a special mission to a hidden village where they have a unique beauty ritual. As he participates in it, perhaps to gain the trust of the villagers or to unlock a hidden power, he undergoes a transformation. This transformation could be both internal and external, making him more handsome as he gains new confidence and skills. He might come back to Konoha looking completely different, causing a stir among his friends and foes alike.
One possibility could be that Naruto starts taking better care of himself. Maybe he learns some new jutsu that has an unexpected side effect of enhancing his appearance. For example, a jutsu that purifies his chakra more effectively also clears up his skin and gives him a healthy glow.
One possible plotline could be Naruto being exposed to some sort of dark jutsu that warps his mind and makes him idolize Tobi. He might start to adopt Tobi's methods and goals, causing chaos in the ninja world. His friends would be shocked and try to bring him back to his senses.
One possible plotline could be that Naruto is cursed by a powerful dark jutsu during a battle. This jutsu slowly transforms him into a demon. As he changes, his friends initially try to find a way to reverse it. But Naruto starts to gain new powers that he must learn to control, and he has to struggle between his human side and the emerging demon nature.
One possible plotline could be that Naruto is exposed to a dark and powerful jutsu that gradually transforms him into a monster. He might start to lose his sense of self and his friends have to find a way to reverse the process. For example, Sasuke could use his Sharingan to try and understand the nature of the transformation and look for a weakness in the dark jutsu.
One possible plotline could be that Harry discovers Snape's past and the reasons behind his harsh behavior. For example, Harry might find out about Snape's love for his mother. This new understanding could lead to an initial truce between them. They could start by working together on a difficult potion in the classroom, with Harry being more patient and Snape being less critical. As time passes, they might find themselves sharing their thoughts about the wizarding world's future and realizing they have more in common than they thought.
One possible plotline could be Bill trying to understand human emotions. As a being that was previously non - human, he might struggle with things like love, friendship, and compassion. He could start off being very cold and calculating, but as he experiences more human interactions, he begins to change.
One possible plotline could be a comical take where Naruto, perhaps as a baby or in a situation where he's regressed to a younger state in diapers, accidentally uses his newfound baby - like clumsiness to his advantage in a prank - like way against his friends. For example, he might 'accidentally' spill something on someone while being carried, leading to a series of funny events.
One possible plotline could be that Naruto and Ino are on a mission together. They start off bickering like they used to in the original series, but as the mission progresses, they begin to understand each other better. For example, they might face a powerful enemy that forces them to rely on each other's unique skills. Naruto's brute strength and Ino's mind - control abilities could complement each other in combat. Another plotline could be a more emotional one where Ino helps Naruto deal with his inner demons related to his past. She could use her skills to get inside his head in a more positive way and help him come to terms with things.
Perhaps a plot where Himawari discovers a new and rare chakra ability, and Naruto helps her to understand and control it. They might go on a journey to find someone who can further teach her about this power. This could involve meeting old friends of Naruto's along the way and having various adventures together.
In a Naruto becomes immortal fanfic, it could be possible through some unique jutsu. Maybe he discovers a long - lost forbidden jutsu that halts the aging process. For example, he might find a scroll in an ancient ruin that contains the knowledge of immortality. Another way could be through some sort of pact with a powerful and immortal being. This being could grant Naruto immortality in exchange for a great service or sacrifice.