One way Percy Jackson could obtain Mjolnir in fanfiction is through a quest. Maybe the Norse and Greek gods come to an agreement for some reason. The gods set up a series of challenges that Percy must complete. These challenges could test his courage, strength, and wisdom. If he passes all of them, he is deemed worthy and is given Mjolnir as a sort of temporary loan or gift for a specific purpose, like saving both the Norse and Greek realms from a common threat.
Percy Jackson could obtain Mjolnir in fanfiction if there is some sort of magical interference. Let's say a powerful magician or a new type of monster has the ability to manipulate magical items. This entity causes Mjolnir to be sent to Percy's world. Percy, being in the right place at the right time, picks it up. Or perhaps the Fates themselves decree that Percy should have Mjolnir to face an upcoming apocalyptic event. So they manipulate the circumstances to make it possible for Percy to get his hands on the hammer.
In some fanfictions, it's possible for Percy Jackson to lift Mjolnir. Fanfiction often plays with the rules and universes of different stories. If the writer decides to bend the rules a bit or create a special scenario where Percy has the qualities that Mjolnir deems worthy, like being brave, selfless, and noble, then he could potentially lift it. It's all about the creativity of the fanfic author.
One possibility could be that Percy, being a demigod with his own set of powers, would have an interesting dynamic with Mjolnir. His ability to control water might interact in strange ways with the lightning powers associated with the hammer. Maybe he could use the hammer to call down lightning into the sea, creating massive steam explosions for combat or to clear a path through the water.
If Percy Jackson were to wield Mjolnir in fanfiction, it would change his status among the gods. The Olympian gods might see him as a threat or as an equal, depending on how he uses the hammer. The Norse gods, on the other hand, would likely be very interested in this demigod who can lift their most powerful weapon. Percy would have to navigate the politics of two different pantheons. He might also use the hammer to protect Camp Half - Blood from new and more powerful threats, like ancient Norse monsters that are drawn to the power of Mjolnir.
In fanfiction, if Percy lifted Mjolnir, it would create an interesting dynamic. Firstly, it would probably shock all the characters around him. Thor might be especially intrigued or even a bit jealous. Percy could use the hammer's power to fight new and more powerful enemies. He could also use it to travel in a different way, perhaps faster or through different realms. And his relationship with the Norse gods would become very complicated. They might see him as a threat or an ally depending on how he uses the power of Mjolnir.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). There are often tags related to 'Percy Jackson' and 'Mjolnir' that can help you narrow down the search. Some writers might combine the world of Percy Jackson, which has its own rich mythology, with the power of Mjolnir from Norse mythology in really interesting ways.
One common theme is the power struggle. Mjolnir is an extremely powerful weapon in Norse mythology, and in fanfiction, it often creates a situation where Percy or other characters have to deal with the new - found power. For example, they might struggle to control it or face the consequences of misusing it.
In fanfiction, if Percy Jackson uses Mjolnir, it could lead to some really interesting power combinations. Percy already has his water - based powers from being a son of Poseidon. Mjolnir gives the power of thunder and is a symbol of Thor's might. Percy might be able to use the hammer to control storms in a different way, perhaps combining water and lightning to create more powerful attacks. He could also use it as a physical weapon, which would be a change from his usual sword, Riptide.
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.
Well, in some fanfictions, Percy might obtain the spear as a gift from a minor god who sees his potential. For example, a god of an ancient and forgotten war cult could give it to him, seeing Percy as a worthy warrior to carry on their legacy.
In some fanfictions, he might find it in an ancient weapon stash hidden in a mythical location. Maybe while on a quest, he stumbles upon a secret chamber where the katana is kept as a powerful relic from an old civilization.