One idea could be Harry travels back in time and accidentally becomes the Dark Lord. Maybe he tries to use his knowledge of the future to rule the wizarding world in a different way, thinking he can prevent future disasters but ends up going down a dark path. Another plot could be that Harry goes back to change something about Voldemort's past, but in doing so, he gets stuck in a time loop where he keeps repeating the same actions over and over again. A third idea is that Harry travels back and teams up with a young Voldemort, believing he can change him, but Voldemort manipulates Harry instead.
Here's some plot ideas. Harry could time travel and end up in a parallel universe where he is the Dark Lord from the start. He has to figure out how to get back to his own universe while dealing with the consequences of his actions in this new one. Or, he travels back and meets a young Tom Riddle before he became Voldemort. Harry tries to befriend him and change his path, but his presence actually accelerates Tom's descent into darkness, and Harry has to find a way to fix it. Also, perhaps Harry goes back in time and his time - traveling spell goes wrong, fusing his soul with Voldemort's in the past, and he has to fight this new, combined dark influence within himself.
One interesting plot could be exploring the Dark Lord's early years before he became so evil. Maybe there were certain events or people that influenced his path. Another idea is a story where Harry Potter has to face the Dark Lord in an alternate magical realm, with different rules and challenges. And a third could be a fanfic where the Dark Lord has a change of heart due to some magical encounter, which completely changes the dynamic between him and Harry.
One interesting plot could be Harry Potter, as the Dark Lord, having to balance his newfound power with the relationships in his harem. Each character in the harem might have different motives and loyalties, creating internal power struggles within the group.
In a 'Harry Potter Dark Time Travel Fanfic', a character could travel back to the time of the first great wizarding war. They could attempt to save lives that were lost in that conflict, but in doing so, they unknowingly create new threats. For instance, saving a certain wizard might lead to that wizard being corrupted later and causing even more destruction.
One interesting plot could be the main character using time - traveling magic from the Harry Potter world to change key events in the Lord of the Time's story. For example, they might go back to prevent a certain dark wizard from obtaining a powerful time - related artifact.
There are stories where the Dark Lord time - travels and ends up changing the prophecy related to Harry Potter. By going back in time, he manipulates events so that the prophecy is either never made or is altered to his advantage. This creates a whole new set of challenges and opportunities in the wizarding world. Some fanfictions also explore how his time travel affects the relationships between different magical families, as he may try to pit them against each other in the past to create chaos and weaken potential opposition in the future.
One great 'Dark Lord Harry Potter Time Travel Fanfiction' is 'The Man Who Conquered Time'. It has an interesting take on Harry going back in time and changing the course of the wizarding world. The story is filled with intense battles and moral dilemmas as Harry tries to prevent the rise of the Dark Lord in a different way.
One idea could be a character going back in time to prevent a major dark wizard event that was overlooked in the original series. For example, they might try to stop the initial rise of Voldemort before he became so powerful.
Well, perhaps Harry travels back in time to the very beginning of the wizarding world. He discovers secrets about magic that have been long forgotten. He then uses this knowledge to make the wizarding world more inclusive and less divided by blood purity. Or he could time - travel during his own time period, like going back to his first year at Hogwarts over and over again to change small things that have big consequences in the future, like making sure Neville is more confident from the start.
Another plot could be that they travel back to the time when the Chamber of Secrets was first opened. Ginny, having been possessed by Tom Riddle in her own time, could use her knowledge to stop the young Voldemort from causing so much harm. Harry could also help by using his skills and knowledge of magic from his own time to combat the basilisk and keep students safe.
Well, a plot could be that a character from the future, like a descendant of Harry Potter, travels back in time to the time of the Triwizard Tournament. This character could have some knowledge of future threats and tries to prevent certain events during the tournament that could lead to greater disasters in the future. They might try to stop Voldemort's minions from using the tournament as a cover to carry out their evil plans. They could also try to make sure that Cedric Diggory doesn't die, which would have a huge impact on the wizarding community as he was a very popular and promising young wizard.