Perhaps a plot twist could be that the Ministry of Magic tries to interfere with Harry's pregnancy because they fear the implications it might have on the wizarding society. They could try to force Harry into hiding or even attempt to separate him from Charlie. However, Harry and Charlie, with the help of their friends, fight back against the Ministry's unjust actions. This would not only create a lot of drama but also show the strength of their relationship and their determination to protect their family.
One interesting plot twist could be that Severus and Harry are forced to marry for political reasons in the wizarding world. Maybe there's a threat from a dark force and their union is seen as a way to unite different factions. Another could be that they initially hate the idea but gradually fall in love as they discover things about each other they never knew. For example, Harry might learn about Severus's deep - seated loyalty to Dumbledore and Severus might see Harry's strength beyond his Gryffindor bravado.
Another plot could be that Charlie and Harry are working on a special project together. During this time, they fall in love and Charlie gets pregnant. But there are outside forces, like a rival group that wants to stop their project. So they not only have to deal with the pregnancy and their relationship but also fend off the threats to their work and future as a family.
In certain fanfictions, a plot twist is that Harry doesn't kill Voldemort directly. Instead, he uses his love and friendship magic in a very unique way. He manages to make Voldemort see the error of his ways, and Voldemort sacrifices himself to undo all the evil he has done. This is a very different take from the usual 'kill or be killed' scenario. Another interesting plot twist could be that the killing of Voldemort reveals a long - hidden prophecy about Harry that has nothing to do with the original prophecy, and this new prophecy sets Harry on a whole new path of discovery and adventure.
In some of these fanfictions, a really cool plot twist is that Fem Harry has an unknown magical heritage on her mother's side that gives her powers that are very different from normal wizarding abilities. This makes her stand out even more in the Weasley family. The Weasleys then have to deal with the jealousy and envy of other wizarding families who want to use Fem Harry's powers for their own gain. Also, she might be able to communicate with the portraits in Hogwarts in a way that no one else can, which leads to her getting crucial information about the school's history and secrets.
Well, in some fanfictions, a plot twist might be that Draco and Harry are forced to marry by a magical contract that was hidden for ages. And as they try to break it, they actually fall in love. Or perhaps a twist where Draco is actually a spy for the good side all along and their marriage is part of a grand plan to expose the remaining Death Eaters. There could also be a twist where Harry loses his memory and Draco has to make him fall in love with him all over again while dealing with the wizarding world's reaction to their union.
One interesting plot twist could be that Jasper's vampire abilities are used to protect Harry from a new and unexpected dark magic. For example, Jasper might be able to sense a dark wizard's intentions before they attack Harry. Another twist could be that they discover a hidden connection between the wizarding world and Jasper's vampire world, like a shared ancient magic that only they can unlock together. It could also be that Jasper's ability to control emotions helps Harry deal with his own inner turmoil caused by Voldemort's presence, in a way that no one else in the wizarding world can.
It could be a story full of unexpected twists. Maybe Charlie and Harry are in a secret relationship. Then the pregnancy would add a whole new layer of drama, like how they deal with their families and friends finding out.
One interesting plot twist could be that the pregnancy is a result of a magical spell gone wrong. Maybe a witch with a grudge against Elena cast a spell that made her pregnant with Elijah's child against their will. This would add a lot of drama as they have to figure out how to reverse it while also dealing with the reactions of their friends and family.
One interesting plot twist could be that Hermione and Harry discover their relation much later in their Hogwarts years. Maybe they've always had a special bond but just attributed it to their friendship. Another could be that their shared heritage gives them unique magical abilities that no one else has, like a combined spell -casting power that can defeat the darkest of dark wizards.
One interesting plot twist could be that Voldemort actually has a change of heart. Maybe in the fanfiction, he realizes the futility of his dark ways after seeing the strength of Harry's love and friendship. Another could be that Harry discovers a new, unexpected power within himself that is not related to his typical Gryffindor courage or his connection to Voldemort's soul pieces. For example, he might find he has the ability to manipulate time in a way that gives him an edge in the battle.