One popular 'Avengers summoned Harry Potter' fanfic is 'Avengers: The Magic Convergence'. In this fic, the Avengers are somehow magically transported to the wizarding world of Harry Potter. Another good one could be 'When the Avengers Meet Hogwarts', which details the interesting interactions and adventures that occur when the two groups come together.
One interesting plot point is often the clash of cultures. The Avengers come from a world of technology and modern values, while the wizarding world of Harry Potter has its own set of traditions and magic - based ethics. Another is how the different powers interact. For example, Iron Man's technology might interact in unexpected ways with magic spells.
Well, perhaps in this fanfic, the Goblet of Fire might summon Harry in a different way than in the original story. Maybe it has a mind of its own and specifically targets Harry for a more dangerous and secretive task that the original Triwizard Tournament didn't include.
Often, heroes from other well - known fantasy worlds are summoned. For example, characters like Aragorn from 'The Lord of the Rings' might be summoned. His skills as a warrior and leader could be very useful in the Harry Potter universe. Another common summoned hero could be Conan the Barbarian. His brute strength and survival instincts would make for an interesting addition to the story. Sometimes, heroes from modern superhero stories are also summoned, like Batman or Superman. Their unique abilities and moral codes would create a lot of interesting scenarios in the wizarding world.
There is also a possibility that the main antagonist is the Goblet itself if it has been corrupted by some ancient dark magic. It could be summoning Harry not for a normal Tournament but to sacrifice him or use his power for some evil purpose, making the Goblet the force that Harry has to fight against.
Well, he could bring his magic skills to the team. Maybe he could use spells to enhance the Avengers' weapons or defenses. For example, he could put a protection charm on Iron Man's suit to make it even more resistant to attacks.
Another theme is the teamwork aspect. Both Harry Potter and the Avengers rely on teamwork. Fanfics often explore how the characters from the two universes would work together, like Hermione and Bruce Banner collaborating on some scientific - magical research.
First, you need to understand the characters well. Know their personalities, powers, and goals. For example, Thor is a powerful Asgardian with his hammer (or axe in Endgame), and Harry Potter is a young wizard with a strong sense of justice. Then, think of a plot that can bring these two universes together. It could be a crossover of villains, like Loki and Voldemort teaming up.
One great fanfiction could be 'The Summoning of Sebastian by Harry Potter'. In this story, Harry might summon Sebastian for a special mission. Maybe it's to solve a mystery in Hogwarts that only Sebastian's unique skills can help with. It could involve a lot of magical elements like complex spells and ancient artifacts.
It could be that the Order has a plan that only Harry can be a part of. His unique experiences and skills, like his ability to resist the Imperius Curse and his connection to Voldemort, are valuable. So they summon him to put these to use in their fight against the Dark side.