In some fanfictions, the time travel necklace might be used to bring back a loved one who was lost. For example, a character could go back in time to save their friend or family member from a tragic event. They would then have to deal with the consequences of changing the past, such as how it affects the present and future relationships and events in the wizarding world.
Well, a cool plotline is when the Golden Trio travels back to the Triwizard Tournament. They could use their future knowledge to help Cedric survive. Maybe they can stop Barty Crouch Jr. from impersonating Mad - Eye Moody and causing all that chaos. They might also be able to change how the tasks are completed, making it more of a fair competition. And think about the interactions they'd have with the other champions! They could form alliances and share magical knowledge that wasn't available at that time.
One plotline could be Luna traveling back in time to meet the founders of Hogwarts. She could use her unique insights to help them with some early challenges they faced, like how to deal with magical creatures in the Forbidden Forest. This would be interesting as it shows Luna's wisdom applied to a very different time in Hogwarts' history.
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.
In some fanfictions, Harry's time - mastery allows him to interact with past versions of himself. This can create really complex and mind - bending scenarios. He could use these interactions to gain wisdom from his past experiences more directly, or to give his past self crucial information that would help him in his battles against Voldemort. For instance, he might tell his younger self about a hidden weakness of a particular Death Eater that he discovers in the future.
One interesting plotline could be Harry and Draco accidentally traveling back to the time when their parents were at Hogwarts. They might see how their parents interacted and how the whole wizarding world was different then. Another could be them traveling to a future version of Hogwarts and seeing the changes in magic education and the social structure among witches and wizards.
One interesting plotline could be that Harry and Luna travel back in time to prevent the death of Sirius Black. They might use their knowledge of future events to outwit Voldemort's minions and change the course of that tragic event.
Perhaps a plot where the founders travel back in time to their own era but with memories of the future. This could lead to them making different decisions in founding Hogwarts, like adding more modern - day safety measures from the start.
One interesting plotline could be Harry using his future knowledge to prevent certain tragedies. For example, he might stop the death of his parents earlier, which would completely change the course of the wizarding world. He could also use his knowledge of dark magic threats to better prepare the wizarding community, like warning about Voldemort's rise much earlier.
Well, in some 'Harry Potter goes back in time' fanfics, Harry might go back to his first year at Hogwarts. He could then use his more advanced magical skills (from his future experiences) to solve the mystery of the Philosopher's Stone in a completely different way. This might involve him befriending different people earlier or even changing the course of how the challenges in the dungeon were set up.
One plotline could be a character using the Time - Turner to save a loved one who died in a previous battle. They go back in time, try to change the outcome of the battle, but end up creating a whole new set of problems because of interfering with time.