A great fanfiction idea could be that James Potter time - travels during a crucial battle in the wizarding world. He travels back to a time when the dark forces were just starting to rise. With his future knowledge, he could start preparing the wizarding community earlier. He could train young wizards and witches in advanced defensive magic, and try to change the course of history so that the big battle he left behind would have a different, more positive outcome.
One great fanfic in this genre is 'Back to the Start'. It has an interesting plot where Harry goes back in time and meets his father, James. The interactions between them are really well - written, showing a different side of James Potter.
A plot could be that James Potter travels back to the time when Voldemort was still Tom Riddle at Hogwarts. He could try to influence Riddle in a positive way, perhaps by befriending him and showing him a different path than the dark one. However, he has to be careful not to change the future too much or risk endangering his own existence and that of his family.
The theme of self - discovery is also prominent. As Harry spends time with James in the past, he learns more about himself. For example, he might realize that he has some of his father's traits that he didn't recognize before. And then there's the theme of friendship. Harry might see how James interacted with his friends and learn from that, or even form new friendships in the past.
FanFiction.net also has time - travel Harry Potter fanfictions. Some might focus on Hermione using a time - turner in a more creative way than in the original books. You can read the summaries and reviews of these stories to figure out which ones are worth reading. There are stories that explore the consequences of changing the past and how it affects the future of the wizarding world, which adds an extra layer of intrigue to the fanfiction.
One possible fanfiction could involve Bellatrix going back in time to try and change the outcome of the Battle of Hogwarts in her favor. Maybe she uses time - turners or some dark magic to travel back. She could attempt to kill Harry Potter as a baby before he even becomes a threat.
One great fanfiction could be 'Lily and James: A Love Beyond'. It delves deep into their relationship before Harry was born. It shows how they met at Hogwarts, their initial dislike which gradually turned into love. The story also includes their adventures as members of the Order of the Phoenix and how they fought against the Dark forces side by side.
One great James and Lily Potter time travel fanfiction is 'Back to the Beginning'. It shows their journey back in time and how they interact with their past selves. It has a great plot with lots of emotional moments.
One great James Sirius Potter time travel fanfiction is 'Back in Time with James'. It has an interesting plot where James travels back to the Marauders' era and tries to fix some family issues. The author does a great job of portraying the different eras and how James adapts to the past.
One interesting Slytherin time - travel fanfiction could be about a Slytherin student who discovers a time - turner hidden in the Slytherin common room. They use it to go back in time to try and change the way Slytherin is perceived in the wizarding world. Maybe they go back to the time of Salazar Slytherin himself and learn the true intentions behind his actions, which were perhaps misinterpreted over the years.
One possible fanfiction could be that Draco, after realizing the error of his ways, uses a time - turning device to go back in time. He teams up with Harry Potter to prevent certain dark events from occurring in the wizarding world. They might work together to stop Voldemort's rise to power earlier, changing the fate of many characters.