Well, perhaps in the fanfiction, Harry has to deal with the challenges of being a single father to Teddy. He might struggle with balancing his work at the Ministry and taking care of Teddy, which could lead to some really heart - warming and also tense moments. For example, he has to miss an important Ministry meeting because Teddy is sick.
A possible plot could be Teddy growing up with a special connection to Harry's past. Since Harry is his father in this fanfiction, Teddy could start having dreams or visions related to Harry's battles against Voldemort. This could then lead to Teddy having a strong desire to become a great wizard like his father and they could train together to face new threats in the wizarding world.
Perhaps Teddy gets into trouble at Hogwarts, and Harry and Ginny have to step in to sort things out. It could involve Teddy being wrongly accused of something, and they use their skills and influence to clear his name. Or Teddy discovers a secret room in Hogwarts that only he can access, and he enlists Harry and Ginny to explore it with him.
A great plot might be that Teddy time travels to a time when Harry was a child living with the Dursleys. Teddy could try to secretly protect Harry from some of the bullying and neglect he endured. Or perhaps Harry and Teddy travel to a time long before Hogwarts was founded to learn about the origins of magic in the wizarding world, and they bring that knowledge back to their own time to help improve modern magic.
They could time - travel to a time in Hogwarts' history when a great mystery was unsolved. Harry and Teddy could work together to figure out what really happened. For example, they might explore the mystery of the Chamber of Secrets long before Harry's own encounter with it. Teddy's inquisitive nature and Harry's experience could lead them to some amazing discoveries.
A possible plot in the Harry Potter Teddy time travel fanfiction could be Teddy going back to the time of the founders of Hogwarts. He could be a sort of mediator between the four founders, especially if there were some disputes or misunderstandings that led to future problems in Hogwarts. Teddy could use his knowledge from the future to try and smooth things over. This would not only change the history of Hogwarts but also have a big impact on the future wizarding world he comes from.
One idea could be Teddy Lupin having trouble adjusting to Hogwarts due to his unique situation, and Harry helps him navigate the challenges. Harry could share his own experiences of feeling out of place as a young wizard. For example, Teddy might struggle with his Metamorphmagus abilities and Harry, having faced many odd situations himself, gives him advice on how to control it and not let it make him stand out too much in a negative way.
In this fanfiction, a plot could be Teddy getting into trouble with the Ministry of Magic for some accidental magic gone wrong. Harry has to use his influence and experience to get Teddy out of the situation. Along the way, they could bond over their shared experiences of being different in the wizarding world. Harry could also introduce Teddy to his friends from the old days, like Hermione and Ron, and Teddy could learn valuable life lessons from them. This would not only strengthen their relationship but also help Teddy grow as a person and a wizard.
A third idea might be that both Harry and Teddy accidentally travel to a time in the past where a great magical event took place, like the founding of Hogwarts. They have to figure out how to get back to their own time while also trying not to disrupt the events that are crucial to the wizarding world's history. They might even learn some long - lost spells or magical knowledge during their time there.
One idea could be Teddy time - traveling back to the time when Harry's parents were alive. He could try to prevent their deaths, which would create a whole new timeline. Harry would then have a very different life, perhaps growing up with his parents and without the burden of being 'the boy who lived'.
Hermione and Ron would probably be there. They are Harry's best friends, so they might be like aunt and uncle to Teddy. They could help Harry out with raising Teddy, like Hermione giving educational advice.
One plot idea could be that Hermione and baby Teddy travel back to the time of the founders of Hogwarts. There, Hermione uses her knowledge to help the founders with some magical problems they are facing, while Teddy, being a metamorphmagus, unknowingly reveals some future magical abilities to the wizards of that time, causing a stir. Another idea is that they travel to a time during Voldemort's first rise to power. Hermione tries to find a way to stop him earlier, with Teddy's unique abilities helping them to blend in and gather information. For example, Teddy could change his appearance to look like a Death Eater's child to get close to their secrets.