Perhaps a plotline where the magic in the 'next world' has different rules. The characters from the original Harry Potter world have to adapt to these new magical laws. This could lead to some really unique and exciting magical duels and problem - solving situations.
A possible plotline could be the interaction between the living characters in the Harry Potter world and the spirits or ghosts from the 'next world'. They might have to team up to fight a common enemy that threatens both worlds, like a powerful dark wizard who has found a way to bridge the gap between the two realms.
One interesting plotline could be about the characters exploring magical realms that are hidden between this world and the next. For example, they might discover ancient spells or magical creatures that were thought to be extinct. Another could involve the spirits of dead wizards guiding the living through difficult times, adding a new layer of mystery and magic to the story.
Well, one plotline could be the main character, perhaps a new healer at Hogwarts, dealing with magical maladies that are beyond the usual. For example, they might encounter a spell - induced illness that spreads among the students and has to find a unique cure using both traditional and forgotten healing methods.
Perhaps in the fanfic, Harry is turned into a snake for a period of time. As a snake, he experiences the wizarding world from a different perspective. He has to learn how to survive as a snake while still trying to fulfill his role in the fight against Voldemort. He might encounter other snakes that are either friendly or hostile, and he has to use his wits to deal with them.
Since this is an improper concept for the Harry Potter world, there are no so - called 'good' plotlines in such fanfic. We should uphold the positive values that J.K. Rowling intended in the original work, rather than exploring such unseemly fan - created ideas.
Well, perhaps in 'the king harry potter fanfic', there's a plotline where Harry discovers a long - lost magical artifact that gives him the power and status of a king. This could lead to him having to face off against old enemies who now see him as an even greater threat. And his friends from Hogwarts might have to band together to protect him as he adjusts to this new role. Also, it could involve new magical creatures being drawn to him because of his new - found king - like aura.
A great plotline in some fanfics is the discovery of new spells and magic. It could be that a long - lost spellbook is found, and the characters start to experiment with spells that are more powerful and dangerous than what they are used to. This could lead to all sorts of situations, from accidentally creating new magical disasters to using these spells to fight off new, unexpected enemies.
One interesting plotline could be Voldemort being redeemed. It's a really different take as in the original books he's pure evil. But in fanfic, some writers explore what if he had a change of heart.
In some fanfictions, the time travel might lead to preventing a certain tragedy that had occurred in the past. For example, they could stop the death of a beloved character, which would then have a ripple effect on the future they come from. This could create a whole new world order in the 'next gen' timeline.
Perhaps Naruto befriends Harry Potter and they exchange their skills. Naruto could teach Harry some of his chakra control techniques, and Harry could show Naruto how to use a wand properly. This interaction could lead to new adventures and ways to fight against the dark forces in the Harry Potter world.
One interesting plotline could be the protagonist using their modern - day knowledge to introduce new magic concepts in the wizarding world. For example, they might find a way to combine Muggle technology with magic in a unique way.