Maybe it could be about Harry experiencing the Beltane festival. He might encounter magical creatures specific to Beltane, like enchanted fire sprites. He could also participate in the traditional Beltane celebrations such as the maypole dance and bonfire lighting, and along the way, he might learn about the significance of Beltane in the wizarding world.
Well, in 'harry goes to beltane fanfic', perhaps Harry is invited to a Beltane gathering. There, he discovers ancient Beltane magic that has been lost for ages. He could get involved in a quest related to protecting the Beltane traditions from dark forces that want to corrupt them. He would then use his Gryffindor courage and his magic skills to safeguard the festival and its magic.
There could be other Hogwarts students. For example, Neville could be there, exploring the different plants and herbs that are associated with Beltane. Luna Lovegood might also make an appearance, with her unique perspective on the magical aspects of the festival. And perhaps some local wizards and witches from the area where the Beltane celebration is taking place.
Well, it could be about Harry participating in the Beltane celebrations. Maybe he helps with the traditional bonfire, or he could be involved in the Maypole dancing. He might also meet some magical creatures that are associated with Beltane.
Hermione could be there. She might be the one explaining the significance of Beltane to Harry. Ron could also be present, probably more interested in the food at the Beltane celebration.
It can add a new layer of magic. For example, if Beltane is a time when dark magic is weakened, it could be a crucial time for the heroes to take on the villains. So it directly affects the plot by creating a strategic opportunity.
Well, perhaps Harry is tired of all the chaos in the wizarding world. Maybe he decides to go on strike against the Ministry's unfair rules. He could be striking for better treatment of house - elves or more equality among wizards of different blood status.
Well, he might discover a hidden magical realm filled with strange creatures. Maybe he stumbles upon a lost spell that he has to master to get out of this new place.
Well, one possible plot could be that Harry goes to Durmstrang to learn different kinds of magic not taught at Hogwarts. Maybe he discovers a new form of defensive magic there. He could also make new friends who have different views on magic compared to his Hogwarts pals. And perhaps he gets involved in a mystery that is unique to Durmstrang, like an ancient curse on the school or a hidden artifact.
One possible plot could be that Harry is wrongly accused of a serious crime within the wizarding world and is sent to Azkaban. There, he discovers a dark secret about the prison itself, like there being a hidden force controlling the Dementors. He has to use his skills and the loyalty of his friends to expose this secret and clear his name.
Well, perhaps Harry could discover the unique flora and fauna on Pandora. He might meet the Na'vi and learn their ways, like how to ride a banshee. And he could use his magic in unexpected ways in Pandora's environment.
One possibility could be that Harry discovers he has some other magical destiny outside of Hogwarts. Maybe he is taken in by a different group of wizards who teach him their own brand of magic in a hidden location. They might believe Hogwarts is too mainstream or that Harry has a special power that needs to be nurtured away from the school.