He probably has adventures fighting new and different kinds of monsters. The lightsaber would give him an edge in combat against creatures that are used to more traditional weapons.
I'm fairly certain there is. Fanfiction writers often like to cross - over different fictional universes, and Percy Jackson and Excalibur are both rich sources of inspiration. Writers could explore how Percy, with his demigod abilities, might interact with the power and mystery of Excalibur. There could be all kinds of plotlines, from Percy finding Excalibur on a quest to it being a key element in a battle against a new, powerful enemy.
Yes, it is quite popular. Many fans enjoy exploring different relationship dynamics for Percy Jackson in fanfiction, and the 'harem' concept, where he has multiple romantic interests, offers a lot of creative possibilities for writers to play with different character interactions and storylines.
There probably is. Fanfiction writers love to blend different fictional universes. In this case, a 'Harry Potter has a lightsaber' fanfic could involve a lot of creative ideas. For example, the lightsaber could be a magical artifact in the Harry Potter world that has been lost for centuries and Harry stumbles upon it. Or it could be a gift from a mysterious figure from another dimension. The possibilities for the story are really endless.
I'm not entirely sure as it's a very specific fanfiction concept. But it might involve Percy Jackson, a character from the Percy Jackson series, somehow obtaining the Rinnegan, which is from the Naruto universe. It could be a really wild crossover story with Percy using the powers of the Rinnegan in his own adventures.
One possible disease in fanfiction could be a 'god - touch' disease. Since he has so much interaction with the gods, perhaps there's a negative side effect. It could be something that makes his body slowly turn to stone, like Medusa's victims, but in a more gradual and complex way. This would force him to seek out powerful cures and make for a great story.
The plot could involve Percy waking up one day and finding a tail instead of his legs. At first, he's confused and a bit scared. But then he realizes it gives him some new abilities, like super - fast swimming. He could then go on a quest where his tail is both an advantage and a hindrance. For example, it might be hard to move on land, but in water, he can out - swim any monster.
There's also 'Female Percy: A New Heroine'. Here, Female Percy brings a fresh perspective to the story. Her fighting style is different, more fluid perhaps. And her relationships with the gods are also unique. Instead of the typical male bravado, she uses her wits and charm to get through tough situations.