One possible plot could be that Queen Elizabeth discovers she has magical powers and is secretly a part of the wizarding world. She decides to use her influence in the Muggle world and her new - found magical abilities to bring about a new era of cooperation between the two worlds. She could visit Hogwarts and offer her wisdom and resources to help improve the school, while also learning more about magic herself.
The pure - blood families would be the most resistant. They would see Queen Elizabeth as an outsider and someone who doesn't understand the 'pure' wizarding ways. The Malfoys, for example, would try to undermine her at every turn. But the more progressive wizarding families, like the Weasleys, would welcome her. They would see her as a chance to break down the barriers between Muggles and wizards. And the students at Hogwarts would be divided at first, but as they see the positive changes she brings, more and more of them would support her.
One possible plot could be that dark wizards are planning to use Queen Elizabeth as a symbol to gain power in the Muggle world. Harry Potter, being the hero, gets wind of this plot and uses his magic to secretly protect her. He could use spells like the Fidelius Charm to keep her location hidden from the dark wizards.
The international relations of the wizarding world would be redrawn. Queen Elizabeth would use her diplomatic skills to strengthen ties with other wizarding countries. She might also introduce new trade policies. For example, trading magical artifacts for Muggle - made goods that could be useful in the wizarding world. The story could also explore how the wizarding world, under her rule, would interact with the Muggle world on a more regular basis. This could lead to some interesting plotlines, like how Muggles would react to the existence of a wizard - ruling queen and how the wizarding world would keep their secrets while still having a closer relationship with Muggles.
Perhaps Harry Potter is summoned to Queen Elizabeth's court by a dark wizard who wants to use Harry's fame to gain power. Harry has to find a way to escape this situation and also protect the queen from the dark wizard's plans. He might use his knowledge of magic and his Gryffindor courage to outwit the dark wizard and return to his own time, leaving behind a legend in Queen Elizabeth's court.
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.
Perhaps the fan fiction could be set in an alternate universe where Queen Elizabeth is actually a powerful witch who has been secretly ruling both the Muggle and magical Britain all along. The Ministry of Magic is her tool to keep the magical world in check. The plot could revolve around her facing a rebellion within the Ministry by a group who want to expose the magical world to Muggles, and her efforts to stop them while also protecting her double life.
One idea could be exploring the Triwizard Tournament from the perspective of a new, original character. This character could be a transfer student who has a secret ability that helps Harry in some way during the tournament. Another plot could involve a mystery related to the Dark Arts that is intertwined with the events of the tournament, like a cursed object that is affecting the champions. Maybe a long - lost relative of one of the main characters shows up during year 4, causing chaos and confusion as they try to interfere with the events at Hogwarts.
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.
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.