Well, in some fanfictions, Naruto's water - controlling ability could be a gift from a powerful sage. This sage, seeing Naruto's potential and his need for new powers to face upcoming threats, bestows upon him the ability to control water. Another origin could be that Naruto accidentally absorbs the chakra of a water - using enemy during a battle, and this chakra somehow melds with his own, giving him the power to control water.
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.
It could also be a result of a powerful curse or blessing. For instance, he might be cursed by an old enemy with the ability to control time as a side - effect, but he then learns to master it. Or, it could be a blessing from a sage or some other powerful being who sees Naruto's potential and gives him this unique ability to help him save the world.
One possible origin could be some kind of ancient bloodline. Maybe Naruto has a hidden bloodline that was passed down through generations and finally awakened, allowing him to summon angels. Another option is that he got this ability through a special training or a quest. He might have found a hidden place or an old sage who taught him the art of summoning angels.
One possibility is that he inherits it through some sort of bloodline connection that was previously unknown. Maybe there's a distant relative who had the ability to control sand, and it somehow got passed down to Naruto.
One possibility could be some sort of new training he undergoes. Maybe he discovers a hidden jutsu scroll that teaches him how to control and produce fire from within his body. This could be a long - lost technique from an ancient ninja clan.
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.
It could be a result of some ancient jutsu that was passed down but lost in the main Naruto story. Maybe it was a power given to him by a mysterious entity to help him in his journey.
It could be the result of some kind of special training. Maybe he met a hermit who taught him a unique technique to perceive chakra in a visible way. For example, this hermit might have had him meditate in a special chakra - rich area and gradually opened his eyes to the world of visible chakra.
It might be a result of some special training or encounter. For instance, if Naruto had a unique experience during a mission or while training with a new mentor, this could have triggered the unlocking of the chakra chains. It could be that he tapped into a new source of chakra or learned a new technique that enabled this ability.
In the fanfiction, Percy's water - controlling ability might be the key to solving a mystery. Say there's a strange drought in the land, and Percy uses his power to figure out what's causing it. He might discover that there's an evil force sucking up all the water, and then he has to use his ability to fight against this force. This would not only involve his power but also his courage and intelligence, making the plot more complex and interesting.