One great 'pjo avengers crossover fanfiction' is 'The Demigod Avengers'. It has an exciting plot where the demigods from Percy Jackson and the Olympians join forces with the Avengers. The character interactions are really well - written, like when Percy uses his water powers in a fight alongside Thor's lightning.
A unique element is the power combinations. For instance, when Annabeth's strategic mind combines with Captain America's leadership. Another is the cultural clash. The Greek - influenced demigods have a different view of heroism compared to the modern - day Avengers. And the magic in the PJO world interacting with the advanced technology of the Avengers is always interesting.
One idea could be that Percy Jackson finds himself magically transported to Skyrim. He could use his water - bending abilities in the frozen landscapes, perhaps to help deal with frost trolls by using water to freeze their legs or something. Another plot could involve Annabeth Chase coming to Skyrim and using her strategic mind to navigate the political intrigues of the different holds. And maybe a demigod from PJO teams up with a Dragonborn in Skyrim to fight a common enemy like an ancient evil that threatens both their worlds.
For the PJO side, Nico di Angelo could be a great character. His control over the dead could have some really strange and interesting interactions in Skyrim, where there are also undead creatures. On the Skyrim side, Ulfric Stormcloak or Elisif the Fair could be included. Elisif's leadership and Ulfric's military might could be factors when dealing with the demigods. If the demigods get involved in the civil war in Skyrim, their powers could completely change the balance of power. And Luke Castellan from PJO could also be an interesting character to bring in, as his complex personality could add a lot of drama to the crossover story.
For demigods, it could either reinforce their existing views or introduce new perspectives. If a fanfiction delves deeper into a certain aspect of their world like the powers of a god, they might gain a new understanding. Mortals would have a more comprehensive view of the PJO world. They would learn about different characters and their backstories that might not be fully explored in the original books.
It can be considered common. There are a large number of PJO fans out there, and fanfiction is a popular medium in fan communities. Since the official books have a set storyline, fanfiction offers a chance to expand on it, so many 'mortals' (fans) are attracted to it.
One benefit is that it allows you to explore different interpretations of the original PJO world. Fanfiction often takes the existing characters and settings and twists them in new and interesting ways. It can also give you a deeper connection to the fan community as you share in the creativity of fellow fans.
The Assassins, being trained in combat and stealth, would initially be a bit skeptical of the demigods' powers. For example, Ezio might be quite surprised when he sees Percy control water to put out a fire in a narrow alley during a fight. On the other hand, the demigods would be fascinated by the Assassins' gadgets and skills. Annabeth might be very interested in the Assassins' hidden blade mechanism and try to figure out how it works. They would learn from each other, with the Assassins teaching the demigods about urban warfare and the demigods showing the Assassins how to use their powers more effectively in combat.
A big theme is also about power and responsibility. As a mercenary, Percy has power in his skills and abilities, but he also has the responsibility to use them for good. In many fanfictions, he struggles with how far he can go in his mercenary work without compromising his values. For example, he might be offered a large sum of money to do something that goes against his moral code, and how he deals with that is a central part of the story. This theme is explored in different ways in different fanfictions, sometimes more subtly and sometimes more directly.
One tip is to know the original PJO series well. This helps you understand the characters' personalities and backstories in the fanfiction. Another is to explore different platforms where fanfictions are hosted. Some might have better quality stories. Also, don't be afraid to try different genres of fanfiction, like adventure or romance set in the PJO universe.