One interesting plot could be a time - traveling character going back to Tom Riddle's school days at Hogwarts. They might try to prevent him from becoming Voldemort. For example, they could befriend young Tom and show him a different path of magic, one that's more about using it for good and building relationships. This could change the entire future of the wizarding world.
Another plot could be that a time - traveler accidentally brings something from the future to Tom Riddle's time. This object might be a powerful magical item that Tom Riddle then tries to take for himself. The time - traveler has to then race against Tom to get the item back and return to their own time without causing too much disruption to the past.
Perhaps a time - traveling Harry Potter (or someone related to him) goes back to the time when Tom Riddle first started exploring the Dark Arts. Harry could use his knowledge of Tom's future to try and sway him away from the Dark side. He could introduce Tom to the beauty of light magic and the importance of love, which are concepts that Tom was lacking in his upbringing.
In some fanfictions, there could be a time - loop situation. Harry and Tom Riddle keep repeating a certain period of time, and each time they interact, they learn something new about each other. For example, they might start off as enemies but gradually come to understand the reasons behind each other's actions as they repeat the time period over and over again.
One interesting plot could be a time - traveling character going back to Tom Riddle's school days at Hogwarts. They could try to prevent him from becoming Voldemort by befriending him and showing him a different path. For example, introducing him to the power of love and friendship which he lacked in his original life.
One possible plot could be that Harry travels back in time to Tom Riddle's school days at Hogwarts. He could try to prevent Riddle from turning into Voldemort by befriending him and showing him a different path. Maybe Harry uses his knowledge of the future to expose the dark magic that was influencing Riddle at the time.
A possible plot is that a young wizard, who is a huge fan of Harry Potter stories in his own time, somehow gets transported back to Tom Riddle's era. He initially just wants to see the famous Hogwarts of that time. But then he crosses paths with Tom Riddle. He decides to use his knowledge of the future to try and befriend Riddle and change his path. However, he soon realizes that Riddle is far more complex and dangerous than he expected, and his actions start to have unforeseen consequences on the future.
Another plotline could be that both Harry and Tom are sent back in time together. They are forced to work together to get back to their own time. Along the way, they learn more about each other's motives and pasts, which changes their relationship in unexpected ways.
Tom Riddle might be very suspicious at first. He is a very intelligent and cautious person. He would likely view time travelers as a threat to his plans or as a strange new phenomenon that he wants to control. So, he could start by trying to figure out their motives and how they managed to travel through time.
One idea could be that Harry accidentally travels back in time and meets a young Tom Riddle before he fully turns evil. He tries to change Tom's path by befriending him and showing him kindness, which leads to a series of events where the future of the wizarding world starts to change in unexpected ways.
A really interesting take in a fanfiction could be that the Master of Death power in Harry gives him a new form of magic that is completely incomprehensible to Tom Riddle. Harry could use this to his advantage in their battles, always staying one step ahead. The story could also explore how this new power affects Harry's relationships with his friends, as they might be both in awe and a bit scared of his new abilities.
Hermione Granger is often a popular character. She can use her intelligence to figure out the implications of time travel and help Harry or deal with Tom Riddle in some way. For instance, she might research spells to counteract any dark magic that Riddle tries to use during their time - traveling encounters.
The theme of self - discovery is also quite common. The time - traveler often discovers things about themselves, their own magic, and their place in the wizarding world while interacting with Tom Riddle. They might learn about their own family history or the true nature of their magic through the experiences in the past. This can be intertwined with the moral dilemma of whether to interfere with Tom Riddle's life or not, as it could have far - reaching consequences for the future.