Well, Sirius Black could be central. If Harry travels back to the time of the Marauders, Sirius would be right in the middle of the action. He could be a guide for Harry in that time period, and together they could change things for the better. Another character could be Luna Lovegood. Her unique perspective on magic and the world around her might give Harry new insights when he's time - traveling. And of course, Voldemort could be central in a sense that Harry goes back in time to try and prevent Voldemort's rise to power in the first place.
Obviously, Harry Potter himself would be central. But also, Dumbledore could play a big role. Maybe Harry travels back in time and meets a young Dumbledore, and they work together to solve some mystery or change an event that Dumbledore later regretted. Hermione would also be a key character. Her intelligence and love for research could be very useful in exploring the implications of time travel and immortality in the wizarding world.
Obviously, Harry Potter himself. He could be exploring the deeper aspects of his family's magic, passing it on to his kids, or even uncovering secrets about his ancestors.
Hermione Granger could be one. Her intelligence and thirst for knowledge might make her interested in a time - traveling character. Ginny Weasley is also a likely candidate. She's brave and has her own charm. And Luna Lovegood, with her unique view of the world, would probably be drawn to the mystery of time travel. Another potential character could be Pansy Parkinson. Her strong - willed nature might lead her to be part of the harem in a different way compared to the others.
Hermione would be a great character in a time travel scenario. Her vast knowledge of magic and history could either be a huge help or cause some really funny mix - ups. For example, she might try to correct historical inaccuracies she finds during her time travels, but end up changing things in unexpected ways. Dumbledore is another character. If Harry were to travel back in time and meet a young Dumbledore, Dumbledore's wisdom and his own mysterious past could lead to some really interesting and humorous interactions.
Voldemort could still be the antagonist even if they travel back in time. If they go back to a time when he was already active, like when he was at Hogwarts as Tom Riddle, he could oppose their attempts to change the future or disrupt his plans. He might sense their presence and try to eliminate them.
Well, Harry Potter would be at the center. But in addition to his usual friends, some other characters could be main characters as well. For example, Neville Longbottom. He has grown a lot in the original series. In this fanfiction, he could bring his knowledge of herbology to the immortal vacation, maybe using plants in the new vacation place in ways no one has thought of before. Also, Dobby the house - elf could be a main character, as his loyalty and magic could play a big role in the adventures during the vacation.
Harry Potter himself is often a central character in these fanfictions. His journey through time to fix things or gain more knowledge is a common plot. Hermione is also popular as she's the brains and could potentially figure out the complex mechanics of time travel. Another popular character is Draco Malfoy. Writers like to explore his character in different scenarios, especially if time travel allows him to have a different relationship with the other characters.
Hermione is a common character. Her intelligence and love for knowledge make her a likely candidate to be involved in time - travel scenarios. She could use her vast knowledge of magic to navigate the challenges of time travel and often plays a key role in changing or understanding events in the past.
Hermione could be involved. She might follow Harry through time to try and stop him from becoming the Dark Lord or to fix the timeline if he already has. Dumbledore is another character. In the past, he could sense something strange about Harry's presence and try to guide him away from the dark path. Young Tom Riddle would definitely be involved. He could be either an ally or an adversary to Harry, depending on the plot. Maybe he sees Harry as a kindred spirit or as a threat to his own rise to power.
Well, the main character could be a Muggle - born wizard who has always felt a bit out of place in the wizarding world. Traveling through the Harry Potter world would be their way of really understanding and finding their place in it. Or it could be a time - traveling character, perhaps a future wizard who comes back to the time of Harry Potter to study the magic of that era. They could get involved in various adventures during their travels. Also, a group of international exchange students could be the main characters. They would travel around the wizarding world, comparing and contrasting their different magical cultures.
Lily Luna Potter might also be a main character. She has a strong personality and her own set of skills. Her presence in the time - travel plot could bring a different perspective, especially when it comes to interacting with the female characters from the past.