A possible plot twist is that Lucifer has the ability to possess wizards. He takes over the body of one of Harry's closest friends, like Ron. Harry has to figure out how to exorcise Lucifer without harming his friend, all while still dealing with the threats from the Death Eaters. This would add an intense emotional and moral dilemma to the story.
Perhaps Lucifer is actually an ancient dark wizard who was banished long ago and is now trying to return using the chaos of the wizarding war in Harry Potter's time. He could manipulate events from the shadows, and Harry, with the help of Dumbledore's portraits (which have some ethereal knowledge), figures out Lucifer's true identity and purpose, leading to a showdown that combines magic from both universes.
One interesting plot twist could be that Harry's true nature is revealed during a crucial battle. Instead of using his normal wizarding spells, he taps into his Lucifer - given powers and turns the tide in a way that no one expected. But this also makes everyone around him question who he really is.
Perhaps Harry Potter travels back in time and ends up befriending a younger Bellatrix. He could try to influence her to not become a Death Eater. This would create a really complex situation because he has to balance not changing too much of the future while also trying to save her from the dark path. It could lead to some really intense moments where Harry has to hide his true identity and motives from her.
One interesting plot twist could be when Caesar turns out to be a long - lost wizard. This completely changes the dynamic as he then has to learn about his magical heritage while also dealing with the existing Harry Potter world's problems.
In some 'Harry Potter Sith fanfiction', a plot twist could be that a seemingly good character is actually being influenced by Sith powers all along. For example, a teacher at Hogwarts who is secretly using Sith mind - control techniques on students to further their own dark agenda.
In some fanfics, a plot twist could be that a character from The Originals turns out to be related to a major Harry Potter character. For example, it might be revealed that a vampire has a long - lost wizard relative in the Potterverse. It completely changes the dynamics of how the two worlds interact.
A really interesting plot twist in 'Hellsing in the Wizarding World' is when the magic from Hogwarts starts to affect the vampires in Hellsing in unexpected ways. For example, some vampires gain the ability to use wizard spells, which turns the whole story on its head. It makes for a really unique take on how the two worlds can interact on a magical level.
A really interesting plot twist could be when the Daleks, who are known for their technology and destruction, are somehow outsmarted by the magic of a first - year Hogwarts student. It goes against their usual superiority in their own universe.
One interesting plot twist could be that the magic in the Harry Potter world is actually related to the Sekirei power source. So, when the two worlds meet, they start to influence each other's magic in unexpected ways. For instance, spells start to have different effects when cast near a Sekirei. This forces the characters from both universes to re - evaluate their understanding of magic and power. It also leads to new alliances and conflicts as everyone tries to figure out what is going on.
In some fanfics, a plot twist could be that Megatron teams up with Voldemort at first but then betrays him to take over both the wizarding world and the Transformers' home planet. Another twist is when Harry Potter uses his magic to give Megatron a new form that has both magical and technological abilities.
One possible plot twist could be that the activation of Hogwarts Amor (presumably some sort of magic related to love at Hogwarts) has unexpected consequences on the relationships between the characters. For example, it might make enemies suddenly fall in love, which would completely change the dynamics between the houses at Hogwarts. This could lead to strange alliances and rivalries within the school.