Nagini's human form could potentially disrupt Tom Riddle's plans. Since she has human emotions in this form, she might not be as blindly obedient as she is in her snake form. For instance, she could show mercy when Riddle wants her to attack someone, which would be a hindrance to his dark plans.
One possible plot could be Nagini's struggle between her loyalty to Tom Riddle and her own humanity. Maybe she starts to question Riddle's dark deeds as she still has human emotions. For example, she might try to prevent him from harming an innocent person.
Tom's character could become more vengeful. Meeting his father, who may have abandoned him, could make him more determined to prove his worth and power. He might see his father as a symbol of all those who have wronged him, and this could lead to a more rapid descent into darkness.
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.
There might be. Fanfiction writers often come up with creative and unexpected relationships. However, this concept is quite a departure from the original story. It would completely change the dynamics of Harry's struggle against Voldemort (Tom Riddle). It could lead to some very different interpretations of Harry's powers and his place in the wizarding world.
Maybe it's a group of future Ministry of Magic officials who have become corrupted by power. They view Tom Riddle as an anomaly from the past and fear that his knowledge of old magic could disrupt their control over the wizarding world, so they become the main antagonists in his journey.
You could also create a fanfiction where a new character, an orphan just like Tom, arrives at the orphanage. This new character could either be a positive influence on Tom, trying to show him kindness and friendship, or they could be in competition with him for the limited resources or attention in the orphanage. This would add a new dynamic to the story of Tom Riddle in the orphanage.
They can interact as students. For example, if they time - travel to when Tom Riddle was at Hogwarts, they could be in the same classes or clubs. Maybe they join the Duelling Club where Tom Riddle was known to participate. Another way is through chance encounters in the hallways or the library. They could strike up conversations about magic or Hogwarts history.
The self - insert could change Tom Riddle's fate by showing him true friendship. In the original story, Tom Riddle was a lonely boy who turned to dark magic. If the self - insert befriends him and is always there for him, it might make him less likely to seek power through dark means.
In some fanfictions, Hermione might end up in a time - travel scenario where she encounters Tom Riddle before he fully becomes Voldemort. If they had a daughter, the story could explore the girl's struggle with her dual heritage. She might have Hermione's intelligence and determination but also be haunted by Riddle's dark past. It could be a complex exploration of nature vs. nurture.
In some fanfictions, Ginny might start as a naive girl but as she gets involved with Tom Riddle, she becomes more aware of the darker aspects of magic. She could develop a stronger will to resist his manipulations.