Well, his friendship with Hermione could be enhanced in some ways. Harry could use his time - controlling power to give Hermione more time to study or research, which she would surely appreciate. However, it could also create jealousy as Hermione might feel that Harry has an unfair advantage. With Ron, there could be a bit of a rift at first. Ron might feel that Harry is becoming too different and powerful. But as time goes on, they could find a new balance. His relationship with Ginny would be interesting. Harry could use his power to create more special moments for them, but Ginny might worry about the implications of such a powerful ability. His enemies, like Malfoy, would be envious and even more hostile, seeing Harry's power as a threat to their pure - blood ideology.
A possible plotline is that Harry accidentally discovers the time - controlling power while exploring an old, forgotten part of the Hogwarts library. He then has to figure out how to use it without disrupting the fabric of time too much.
Well, Harry Potter himself is surely one of the main characters as the title implies he has the power to control time. Hermione Granger is likely to be another main character. She is always by Harry's side in the original series and would be there to help him understand and manage his new time - controlling ability, perhaps with her vast knowledge and logical thinking.
Obviously, Harry Potter is the main character as the title implies. He's the one with the power to control the elements. Hermione Granger and Ron Weasley would also likely be important characters. Hermione could be helping Harry research about the origin of his element - controlling ability, and Ron would be by his side in his adventures, providing support and some comic relief.
When Harry and Severus go back in time, Severus' relationship with the Death Eaters will surely be affected. He might avoid getting involved with them completely, which would change how the other Death Eaters view him. Harry's relationship with his friends like Ron and Hermione would also be different. Since he is changing the past, the future where he meets them might not be the same. And Severus' relationship with Hogwarts faculty could be improved as he has a chance to start anew without the burden of his past mistakes.
Well, his relationship with Hermione would likely change. Hermione would be both fascinated and a bit envious of Harry's new Dragonborn abilities. She would constantly be trying to study and understand how they work, and might even be a bit bossy about it, like 'Harry, we need to document every aspect of this new power!' Their friendship would still be strong, but there would be a new dynamic of her trying to keep up with his ever - expanding powers.
Definitely Hermione. Since she's Harry's closest friend and very intelligent, she would be deeply involved in any changes Harry tries to make. Also, Snape. Harry's actions in the past could completely change his relationship with Snape. And of course, Voldemort. If Harry goes back far enough, he could potentially stop Voldemort's transformation into the evil wizard he became.
His relationship with the Dursleys might be more complex. They could be even more cruel, seeing him as a burden because of his cancer. Or, in a different take, they might feel a bit of pity and be slightly less horrible. As for his friends at Hogwarts, he might be more guarded at first. He has been through a tough time with his health, so it could take him longer to open up to Ron and Hermione.
Harry's relationship with his enemies would also be different. Voldemort might see him as a more formidable opponent due to his dual nature. He might try to turn Harry's demonic side against the wizarding world. On the other hand, Harry's angelic side could make some of the Death Eaters question their loyalty to Voldemort as they see a glimmer of hope in Harry. Overall, his relationships would be in a state of flux as he tries to navigate his new identity and the reactions of those around him.
The main character is Harry Potter. However, other characters like Luna Lovegood could be important. Her unique perspective on the wizarding world might offer Harry new insights on how to use his reality - controlling powers. And Neville Longbottom could also be involved, perhaps using his new - found confidence to support Harry in his reality - altering adventures.
Ron would be there too. He could be in charge of things like the Gryffindor common room or helping Harry with student relations. And of course, Dumbledore might still have some influence in the background, even if Harry is in control. His wisdom could be a guiding force for Harry as he navigates running the school.