Maybe Harry discovers some dark family secrets that make him question his place on the 'good' side. He could find out that his ancestors had strong ties to dark magic, and this knowledge could slowly corrupt him. He might start to experiment with dark spells, thinking that he can control them and use them for what he believes is the greater good, but gradually slips towards the darkside.
In a fanfiction like this, Harry could be influenced by a powerful dark wizard who manipulates his emotions. This wizard could prey on Harry's feelings of loneliness and the loss of his parents. By making false promises of power and a way to bring his parents back, he lures Harry towards the darkside. Harry, in his desperation, starts to believe in this wizard's lies and begins to embrace the dark magic.
One possible plotline could be that Harry discovers a dark secret about his family and feels betrayed by the wizarding world. This could lead him to side with the dark forces. Another could be that he is influenced by a powerful dark wizard who manipulates his mind. Maybe he becomes envious of the power others hold and decides to take it by any means, turning evil in the process.
It could still be Voldemort. Even if Harry is turning to the darkside, Voldemort might see him as a threat because Harry has his own unique power. Voldemort might not want to share his control over the dark forces with Harry, so he would become the main antagonist in a fight for dominance in the dark world.
One possible plotline could be that Lily, now as a girl, has to navigate the wizarding world all over again. She might face different challenges and opportunities than she did before. For example, she could form new friendships or rivalries at Hogwarts.
A great plotline could be that Harry, now a girl, has to navigate the world of wizarding fashion and etiquette which she previously ignored. She might be forced to attend more social events at Hogwarts, like balls or tea parties, where she has to learn proper behavior. And she could also use her new identity to her advantage when it comes to spying on the Death Eaters. They might underestimate her because she's a girl, but she could outwit them.
In some 'Harry Potter turns into Hermione fanfiction', the plot may involve Harry adjusting to Hermione's physical appearance as well. He might be shocked at first but then realizes the advantages it gives him. For example, he could use Hermione's reputation for being a bookworm to his advantage when it comes to researching dark magic or hidden secrets in the library. And he may also face some difficulties when it comes to Hermione's friendships with other girls, as he has to act like her and keep those relationships intact.
One possible plotline could be that Harry discovers his siren abilities during his time at Hogwarts. At first, he's confused and scared by these new powers. He might accidentally use his siren voice to make a teacher or a student do something they don't want to. Then he has to learn to control it with the help of Dumbledore or another magical creature.
The businessman could be trying to revolutionize the wizarding education system from a business perspective. He sees potential in making Hogwarts more efficient and cost - effective. He proposes ideas like installing modern muggle - like technology for administrative purposes or outsourcing some non - magical aspects of the school's operations. This causes a stir among the Hogwarts staff and students. Another plotline could be that he is a muggle - born who made it big in the muggle business world and now wants to use his wealth and influence to improve the status of muggle - borns in the wizarding world. He funds projects and initiatives that aim to bridge the gap between muggles and wizards.
Perhaps in this fanfiction, there could be a new, unexpected hero emerging. Maybe Neville Longbottom finally steps up in a big way. Since Harry is dead, Neville could be the one to find a new way to defeat Voldemort, like discovering a long - lost spell or uniting the houses in a way that has never been done before.
One possible plotline could be that Harry, after some dark magic influence or a strange accident, starts to show Joker - like behavior at Hogwarts. He might play cruel pranks on his classmates and teachers, using his magic in unexpected and unethical ways.
One possible plotline is that Broly is brought to the Harry Potter world as a result of a powerful spell gone wrong. He initially causes chaos with his strength but then gradually learns about the concept of magic and starts to respect it. Another could be that Broly is a hidden protector of Hogwarts, his Saiyan powers being the ultimate defense against a new dark force that the normal magic in the wizarding world can't handle.