Well, it could be a time - travel fanfic. Harry Potter and his friends travel back in time and meet Queen Elizabeth. They could help her deal with some threats to the throne using magic, and in return, she offers them something valuable in the wizarding world, like a special magical artifact that has been lost in the Muggle world for centuries.
It could be a very interesting fanfiction. Maybe Queen Elizabeth could be a secret witch in the Harry Potter universe. She could use her magic to rule Britain in a different way, perhaps with the help of Hogwarts' magic. For example, she could use spells to improve the economy or protect the country from dark wizards.
A possible scenario is that Queen Elizabeth has a magical artifact that has been passed down through generations in the royal family. This artifact draws the attention of Harry Potter and his friends. They come to her palace to investigate, and she becomes involved in their adventures. She could offer them resources and protection in the Muggle world, while they introduce her to the wonders of the wizarding world.
It might entail Queen Elizabeth as a character in the wizarding world. She could be a guest at Hogwarts, and all the students are curious about her. She might give a speech about leadership and how it's similar in the Muggle and wizarding worlds.
Harry would likely be very curious about the court and its people. He might use his magic in small, discreet ways to amuse the courtiers, like making a flower bloom in his hand. He would probably be polite and respectful, but also a bit of an outsider. His different style of dress and his magic would make him stand out, and he'd have to explain himself carefully to avoid being seen as a threat.
A fanfiction could involve Harry Potter being transported into the world of Snow White. He might mistake the Queen for a dark wizard and try to stop her from harming Snow White. Along the way, he could use his magic skills from Hogwarts to outwit the Queen and protect Snow White, while also learning about the different kind of magic in this new world.
One idea could be that Hulk somehow gets transported into the wizarding world of Harry Potter. Maybe a magical experiment gone wrong by a Hogwarts student creates a portal that sucks Hulk in. He could then cause chaos as he's not used to the magic and strange creatures there.
One idea could be a story where a Wendigo somehow enters the wizarding world of Harry Potter. Maybe it's brought in by a dark wizard who wants to use it as a weapon. The Trio - Harry, Ron, and Hermione - would then have to figure out how to defeat it using their magic and knowledge.
I'm not sure if there are many highly recommended ones. Fanfiction can be a very niche area, and combining 'Harry Potter' with Queen Elizabeth is rather unusual. You might have to search through various fanfiction platforms very thoroughly to find something that stands out.
There could be. Fanfiction writers often come up with the most creative and unexpected crossovers. Harry Potter's world is full of magic and adventure, and imagining him protecting Queen Elizabeth could lead to some really interesting plotlines. But you'd have to search through various fanfiction platforms to find one like that.
One idea could be a crossover where Elizabeth Olsen's character (let's say Wanda from the MCU) is transported to the Naruto universe. She could use her powers in unique ways to interact with the ninja world, like using her chaos magic against ninjutsu. Maybe she teams up with Naruto to fight a common enemy that threatens both their worlds.