Another way could be that it is given to him by a mysterious sea - dwelling being. This being recognizes Percy's potential and the need for a powerful weapon in the face of an upcoming great danger. So, as a gift or a loan, Percy gets the trident.
It's possible that Percy has to earn the trident through a series of quests. He has to complete tasks for different sea deities or creatures. These tasks could involve things like rescuing a sacred sea creature, or retrieving a lost artifact from a sunken ship. After successfully finishing all the quests, he is finally awarded the trident.
He might find it during an underwater adventure. Maybe he stumbles upon an ancient temple dedicated to Poseidon and there, in the center, lies the trident. It could be a test set by Poseidon himself for Percy to prove his worthiness to wield such a powerful weapon.
In some fanfictions, Percy might obtain the trident through a special quest. Maybe he has to prove himself worthy to an ancient sea deity who then bestows the trident upon him as a symbol of power and trust.
One possibility is that Percy uses the trident to explore uncharted areas of the ocean. He discovers ancient underwater ruins that are protected by powerful magic. With the trident, he can navigate through dangerous barriers and uncover secrets about his own heritage and the history of the sea gods.
Perhaps it is given to him by a mysterious figure. This figure could recognize Harry's potential and believe that he is the right person to wield the trident. The figure might be from a different magical culture that has a connection to the trident and sees Harry as a key to some greater purpose.
He could have underwater adventures. The trident might give him the ability to communicate with sea creatures and explore the depths of the ocean. He could discover lost underwater cities or battle against sea monsters.
It might make Percy more confident. With the trident, he has a powerful symbol of his father's support. He could use it to face stronger enemies and gain more respect in the demigod world.
Well, he might find it in some mysterious place like an ancient temple. Maybe it was left there by a powerful being from another dimension.
Perhaps he discovers it in an ancient, hidden temple dedicated to a forgotten god. The sword could be a gift from this god, who sees potential in Percy to use it for good.
In Percy Jackson fanfiction, a character could get a trident tattoo in several ways. One possibility is that it's a gift from Poseidon himself. The god could touch the character's skin and leave the mark of his trident as a sign of favor. Another way could be through a ritual. The character might participate in a ceremony dedicated to Poseidon, and as part of it, they receive the tattoo. It could also be that the character finds an ancient artifact or a magical place where getting the trident tattoo is part of a prophecy or a test.
Well, he might obtain it in a fight. Maybe after defeating an enemy who had stolen Zabuza's sword from its original place. Or perhaps he discovers it in an old, forgotten hideout where Zabuza once stashed his things.
One possibility could be through a forbidden jutsu experiment gone wrong. Maybe some rogue ninja was trying to create a super - powered being and Naruto ended up being the subject. The Sharingan was transplanted into him, but only one eye was successful.