Fem Harry might develop more empathy going back in time. In the original timeline, she faced a lot of hardships which made her a bit more guarded. But going back, she might use her experiences to be more understanding towards others. For example, she could be more patient with Neville, helping him gain confidence earlier. Also, she might be more confident in her femininity compared to her previous self, using it as a strength rather than something to be overlooked in the male - dominated wizarding world.
A cool plot twist might be that Fem Harry goes back in time and discovers that her parents were involved in a secret mission that was never revealed before. This could lead to her having to deal with the consequences of uncovering that truth. Also, she could find out that Voldemort had a different origin or a hidden weakness that was lost in history. As she tries to use this knowledge to defeat him earlier, she might face opposition from some of the older wizards who don't believe her or are afraid of the changes she could bring. It could also be that she changes the way magic is taught at Hogwarts, introducing new spells or techniques from the future that create a whole new set of challenges and opportunities for the students.
She might meet a powerful and mysterious wizard who has been hiding in Vegas for a long time. This wizard could be either a potential ally or an enemy. There could also be a group of young witches and wizards who are having their own adventures in Vegas and they all team up with fem Harry Potter for a wild ride full of magic, mystery, and fun.
One possible scenario in this fanfiction could be that Fem Harry Potter is initially shocked by the unique and alien environment of Pandora. She might struggle to adapt to the different flora and fauna, but her magical abilities could give her an edge. For example, her ability to use magic could help her communicate with some of the intelligent species on Pandora in ways that the regular humans in the Avatar world can't. Maybe she uses spells to understand the language of the Na'vi, which could lead to interesting interactions and alliances.
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.
Well, in this 'Harry Potter goes back in time' evil fanfiction, Harry might go back and change things to benefit Voldemort. Maybe he'd stop Dumbledore from finding out important information or interfere with the Order of the Phoenix's formation. He could also use time - travel to learn dark magic from the past and bring it to the present, causing destruction and fear among the wizarding community.
If Harry Potter goes back in time to teach fanfiction, it would be a really strange and interesting scenario. First of all, the wizarding world might not understand what fanfiction is at first. Harry would have to explain that it's a form of writing where fans create their own stories based on the original. He could inspire young witches and wizards to be more creative with the Harry Potter story itself. Maybe some of them would come up with really unique magical adventures that even J.K. Rowling hadn't thought of. Also, it could cause some chaos as the concept of fan - created stories might be a bit too modern for the old - time wizarding community.
Well, in some 'Harry Potter goes back in time' fanfics, Harry might go back to his first year at Hogwarts. He could then use his more advanced magical skills (from his future experiences) to solve the mystery of the Philosopher's Stone in a completely different way. This might involve him befriending different people earlier or even changing the course of how the challenges in the dungeon were set up.
His father's friends, the Marauders, are very likely to interact with Harry if he goes back in time. He could become a part of their group, learn their secrets, and even participate in some of their pranks. Hagrid is another character. Harry has always had a special bond with Hagrid, and going back in time, he could strengthen that bond even more. And of course, Snape. Harry could try to change their relationship from the start and understand Snape better.
There could be a young Salem witch named Lily. She befriends Fem Harry Potter and shows her around Salem. Lily could be very knowledgeable about the local magic and help Fem Harry Potter understand the differences between Hogwarts magic and Salem magic.