Well, one possible plot could be that the gods in the Percy Jackson universe notice some strange energy disruptions caused by the Infinity Stones in the Avengers' world. Percy and his friends are sent to investigate. They meet the Avengers and at first there are misunderstandings, like the Avengers thinking Percy's powers are from some new form of alien technology. But then they realize they need to work together to stop a common enemy, perhaps a new powerful being that is drawn to the combined power of the demigods and the Infinity Stones.
In a 'Percy Jackson and Avengers crossover fanfic', the plot could be centered around a prophecy. There's a prophecy in the Percy Jackson world that mentions heroes from another realm (the Avengers). Percy and his friends start having strange dreams about the Avengers. Meanwhile, the Avengers are dealing with a new threat that seems to have some connection to Greek mythology. They cross paths and realize that the only way to defeat this threat is by combining their powers. Thor, being from a mythological background himself, helps bridge the gap between the two groups at first, and they embark on an adventure to save both their worlds.
A plot might involve Loki getting his hands on a powerful artifact from the Percy Jackson world. This causes chaos as it starts to affect the balance of power in both universes. The Avengers, not understanding the magic of this new object, call for help. Percy and Annabeth show up. They have to quickly educate the Avengers about the magical world while also trying to figure out how to stop Loki from using the artifact to take over both their worlds. Eventually, they all team up with their unique skills - the Avengers' tech and combat abilities, and the demigods' magic and fighting skills.
One possible plot could be that the Greek gods, noticing the powerful threats the Avengers face, send Percy Jackson and his friends to help. Percy could use his water powers to assist in putting out fires during a battle like the one in New York. Meanwhile, Thor could be intrigued by Percy's connection to Poseidon and they could exchange stories about their godly fathers.
The plot could involve Percy Jackson's world of Greek gods colliding with the Avengers' universe. Maybe the gods have some sort of issue that only the Avengers' powers can help with, or vice versa. For example, an ancient Greek monster has been unleashed in the modern world that the Avengers are struggling to defeat, and Percy and his friends come in with their knowledge of Greek mythology to assist. It could also be a situation where the Avengers are dealing with a threat that has its roots in Greek magic, and they need Percy's demigod powers to counter it.
One possible plot could be that the Avengers are facing a powerful new threat that has some connection to the Greek mythology world. Percy Jackson and his friends are called in to help. Maybe it's a villain who has the power to control both technology like the Avengers are used to dealing with and also the elements of Greek magic. They would have to combine their skills, with Percy using his water - controlling abilities and the Avengers using their high - tech weapons and superpowers to defeat the villain.
One way could be to have Percy Jackson's powers of being a demigod interact with the superpowers of the Avengers. For example, his ability to control water could be used in a joint mission with Thor's lightning powers. Maybe they are facing a common enemy that can only be defeated by combining their unique skills.
One plot idea could be that Percy Jackson discovers a magical artifact that somehow links his world to the Marvel Universe. Thor senses the power of this artifact and comes to investigate, leading to a meeting with Percy. Meanwhile, the Avengers also get wind of it and think it could be a threat. So, they all end up in a big showdown where they have to figure out if they're on the same side or not.
One possible plot could be that Percy and his demigod friends are somehow transported to the Halo universe. They could team up with the Spartans to fight a common enemy, like a new kind of powerful monster that has emerged in the Halo world due to some strange rift between the two universes. Percy could use his water powers in unique ways, for example, to short - circuit some of the Covenant technology which might be vulnerable to water in this crossover scenario.
One possible plot could be that the gods in the Percy Jackson universe sense a great threat from another dimension (the Marvel universe). Percy and his friends are sent to team up with the Avengers. Percy's water powers could be useful in fighting villains like Electro. Annabeth's strategic mind would assist in planning battles against foes like Loki. They all have to learn to work together, with Percy and the Avengers initially having some clashes due to their different ways of handling things.
One possible plot could be that in a world where the gods of Percy Jackson and the Avengers co - exist, Percy is somehow tricked or forced to banish the Avengers. Maybe there's a power struggle among the gods and they see the Avengers as a threat to their power, so they use Percy, who has a strong connection to the divine world, to get rid of them. Percy might be conflicted as he may admire the Avengers' heroism but has to follow the gods' orders.
If Percy Jackson were to join the Avengers, it would be chaos at first. Percy is used to operating on his own or with a small group of demigods. The Avengers are a big, organized team. However, his powers would be a great asset. He could use his water manipulation to put out fires caused by the Hulk's rampages or to flood areas to stop advancing enemies. His loyalty and courage are also top - notch, which the Avengers would come to respect. His connection to Poseidon might also bring in some new elements to the story. Maybe Poseidon could offer some assistance or advice in certain situations. And Percy's experiences with different gods and monsters would give the Avengers new perspectives on the threats they face.
Well, in such a fanfic, there could be epic battles. The Avengers with their superpowers like Iron Man's high - tech suits and Thor's lightning, and Percy Jackson with his water - controlling abilities. Maybe they would team up against a common enemy, like some ancient and powerful monster that threatens both the world of the Avengers and Percy's demigod realm.