I really like 'Time - Twisting Ginny'. In this fanfiction, Ginny travels through time and meets a younger version of Harry. It's a unique take on the time travel concept as it explores their relationship from a different perspective. There are also some great action scenes and magical elements that make it an exciting read.
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.
One popular trope is changing the past. In many Ginny Potter time travel fics, Ginny goes back to fix something that went wrong in the past, like saving a loved one or preventing a dark event. Another is the fish - out - of - water situation. Since Ginny is from a different time period when she travels, her reactions to the past ways of the wizarding world are interesting to read.
One great Harry Potter Ginny Weasley time travel fanfiction is 'Back to the Beginning'. It has Ginny traveling back in time and trying to change some of the events that happened in the wizarding world. The way she interacts with the younger versions of the characters, especially Harry, is really interesting.
Another plot could be that they travel back to the time when the Chamber of Secrets was first opened. Ginny, having been possessed by Tom Riddle in her own time, could use her knowledge to stop the young Voldemort from causing so much harm. Harry could also help by using his skills and knowledge of magic from his own time to combat the basilisk and keep students safe.
One popular theme is changing the past. Fans often write about Ginny using her knowledge of future events to make things better. For example, preventing the death of certain characters or stopping Voldemort earlier.
I really liked 'Time - Twisted Sisters'. In this fanfic, Hermione and Ginny's friendship is explored deeper as they time travel. They face many challenges together, like dealing with different versions of their friends from the past. It's a great read if you like stories that focus on character development during time - travel adventures.
Another theme is changing the past or future. In many of these fanfictions, Ginny tries to fix things that went wrong or prevent bad events from happening. For example, she might try to stop a dark wizard from rising to power in an earlier time period. It adds a lot of drama and suspense to the story.
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 idea could be that Harry and Ginny travel back in time to the Marauders' era. They could interact with James, Sirius, Remus and Peter, and perhaps change some small events that later have a big impact on the fight against Voldemort. For example, they could give the Marauders some tips on how to better hide from Snape, which in turn could make Snape less bitter in the future.