Another plotline might involve Harry making new friends at the secret school who have different backgrounds and powers. They could team up to solve a mystery within the school, like a series of strange disappearances or a hidden treasure.
Perhaps there is a plotline where Harry has to face a powerful enemy that has infiltrated the secret school. He has to use his wits and the skills he's learned at Hogwarts and in this new school to defeat the enemy and protect his new friends and the school itself.
Perhaps in this Irish fanfiction, Harry goes to school and discovers a hidden Irish wizarding tradition related to divination. This could involve a different way of reading the stars or tea leaves that is specific to Irish magic, which adds a new dimension to his magical education.
One interesting plotline could be Harry using his modern magic knowledge in Camelot. For example, he might introduce some simple spells that could be useful for daily life in Camelot like a spell for lighting fires easily. Another could be his interactions with the knights of the Round Table. He might learn their code of chivalry and in turn teach them about loyalty in a different way from his own experiences at Hogwarts.
One interesting plotline could be that Harry's 'going crazy' is due to a powerful dark magic spell that was secretly cast on him. He starts seeing strange visions and having out - of - control magic surges.
One possible plotline could be Harry adjusting to the unique supernatural environment in Sunnydale. He might encounter vampires and other demons that are different from what he's used to in the Harry Potter world. Maybe he forms an unlikely alliance with Buffy and her gang to fight a common, powerful enemy.
One interesting plotline could be Harry making new friends at Stonewall who have different magical abilities than those he knew at Hogwarts. This could lead to new adventures and challenges.
One interesting plotline could be Harry going back in time and preventing certain tragedies from happening in the wizarding world. For example, he might stop the death of his parents. Another could be him using his future knowledge to change the way Hogwarts is run, like improving the curriculum for Defense Against the Dark Arts.
One possible plotline could be Harry making new friends at Durmstrang. He might meet students with different magical abilities and cultures compared to Hogwarts. Another could be Harry facing new challenges in the Durmstrang curriculum, which might be more combat - oriented or have different magical theories.
Perhaps there's a plot where Harry discovers a hidden magical mystery within the walls of Harvard. It could be related to an ancient artifact that has some connection to the wizarding world. He then has to use his magical skills, but also his newfound knowledge from Harvard to solve it.
Maybe Harry decides to go rogue because he's tired of the Ministry's interference. He could form his own group of like - minded wizards and witches to fight against the corruption in the wizarding world. This would involve him recruiting friends and allies, and facing many challenges along the way.
One possible plotline could be Harry's initial shock and confusion upon arriving at the Hellmouth. He might have to quickly adapt to the new and dangerous environment filled with demons and other supernatural threats.