Time travel could make Harry more confident. If he goes back and changes things for the better, he'll see that he has the power to make a real difference. He might become less hesitant and more decisive in his actions.
A possible plot is that Harry travels back to a time when the Marauders were in school. He could become friends with them and try to prevent some of the bad things that happened to them later. He could also use his knowledge of the future to help them in their pranks and adventures. This would be really interesting as he would be interacting with his father and his friends in a whole new way. It could also lead to changes in the future relationships and events at Hogwarts.
I'm not entirely sure. Fanfiction can cover a huge range of ideas, and while time travel in Harry Potter is a common theme, and Orochimaru is a well - known character from Naruto. The combination seems a bit out there. But, if you search on some major fanfiction platforms like Archive of Our Own or FanFiction.net, you might be able to find out for sure if such a fanfiction exists.
A great fanfiction idea could be that James Potter time - travels during a crucial battle in the wizarding world. He travels back to a time when the dark forces were just starting to rise. With his future knowledge, he could start preparing the wizarding community earlier. He could train young wizards and witches in advanced defensive magic, and try to change the course of history so that the big battle he left behind would have a different, more positive outcome.
If they travel back to a time when Ginny was much younger, like when she was a first - year and Harry was a bit older (due to time travel), Harry could become a sort of protector and mentor to her. This would build a different kind of bond. He could help her discover her magic in new ways and she could show him the innocence and wonder of Hogwarts from a young student's perspective. As she grows older in that time period, their relationship could shift from mentor - mentee to a more romantic one in a very unique way.
One great older Harry Potter time travel fanfiction is 'The Time - Turner Conundrum'. In this story, Harry accidentally travels back in time much further than he intended. It's full of interesting twists as he has to deal with a Hogwarts that's very different from what he knows, and he has to figure out how to get back to his own time without changing history too much.
Another interesting fanfiction plot could be about a descendant of Salazar Slytherin who time - travels. They go back to the time of the Basilisk with the intention of taming it. They believe that the Basilisk was misused in the past and that they can change its fate. They might have to face many challenges, like the opposition from other wizards at that time who fear the Basilisk's power.
One possible fanfiction idea could be that a character discovers a time - traveling device while exploring the Chamber of Secrets where the Basilisk once lurked. They accidentally travel back in time to the era when the Basilisk was first created or when Salazar Slytherin was alive. This could lead to all sorts of adventures, like trying to prevent the Basilisk from being created or changing the course of Hogwarts' history regarding the Chamber.
One idea could be a Hufflepuff student discovers a time - turning device in the Hufflepuff common room. They decide to travel back in time to meet the founders of Hogwarts. They end up learning valuable lessons about loyalty from Helga Hufflepuff herself.
I also like 'A Second Chance at Life'. This fanfiction focuses on a character getting a chance to go back in time and correct their mistakes. It's a more emotional take on time travel in the Harry Potter universe. The author does a great job of exploring the character's feelings and how they deal with the knowledge of the future.