Well, a plot could be that Ginny has some sort of premonition about Tom Riddle's future as Voldemort. She then tries to change his path in the lemon fanfiction. This would create a lot of tension and emotional turmoil as she battles with her feelings for him and the knowledge of what he could become. Also, there might be a plot where Tom Riddle is actually conflicted about his feelings for Ginny and his dark ambitions, which makes for a very angsty and engaging story.
Another plot could involve a time - travel aspect. Ginny Lemon could somehow be sent back in time to when Tom Riddle was a student at Hogwarts. She might try to change his path towards the dark side by showing him kindness and understanding, but things could go awry as Tom's ambition and insecurities still drive him towards the dark arts, and Ginny has to deal with the consequences of her actions.
The main characters are obviously Tom Riddle and Ginny Lemon. Tom Riddle is often portrayed as a complex and dark character. He is highly intelligent but also extremely power - hungry. Ginny Lemon, on the other hand, is usually depicted as a brave and somewhat headstrong character. She may be written as a character who is not easily intimidated by Tom's dark presence.
One possible theme could be the allure of the dark side. Ginny was once under the influence of Tom Riddle through his diary. So, in fanfiction, it could explore how that initial allure still lingers and affects their interactions. Another theme might be redemption. Maybe the story could be about Tom Riddle finding a way to redeem himself through his connection with Ginny. And of course, there could be themes of love and attraction, though not in a sexual way as we're avoiding inappropriate content.
One interesting plot could be a time - traveling character going back to Tom Riddle's school days at Hogwarts. They could try to prevent him from becoming Voldemort by befriending him and showing him a different path. For example, introducing him to the power of love and friendship which he lacked in his original life.
One possible plot could be Nagini's struggle between her loyalty to Tom Riddle and her own humanity. Maybe she starts to question Riddle's dark deeds as she still has human emotions. For example, she might try to prevent him from harming an innocent person.
In some fanfictions, Ginny might start as a naive girl but as she gets involved with Tom Riddle, she becomes more aware of the darker aspects of magic. She could develop a stronger will to resist his manipulations.
I'm not really into that kind of fanfiction myself. However, you can try searching on some popular fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a wide range of fanfictions, but make sure to read the tags and descriptions carefully to find what you're looking for.
Perhaps Ginny and Tom both travel to a different time period, like the Middle Ages. There, they have to work together to survive in a world full of magic they don't fully understand yet. Ginny could use her modern knowledge of magic, while Tom's natural cunning helps them navigate the social and political aspects of that time. This could lead to a strange alliance and a re - evaluation of their relationship.
One interesting plot could be a time - travel scenario. Hermione somehow travels back in time to Tom Riddle's Hogwarts days. She tries to prevent him from becoming Voldemort. Maybe she uses her knowledge of magic and the future to show him a different path, like introducing him to the power of love and friendship that he was deprived of as a child.
Well, a possible plot is that Hermione discovers a hidden diary of Tom Riddle that has some sort of magic she has never seen before. As she delves into it, she somehow gets connected to Tom's memories and experiences his past. This could lead to her trying to understand what made him turn out the way he did and she might attempt to change his future. Another plot could be that in an alternate universe, Tom Riddle didn't become evil and he and Hermione meet at Hogwarts as normal students. They end up competing in academics and gradually develop a strange sort of friendship that challenges both of their beliefs.