Perhaps a major plot twist is that the reason Harry becomes the new Dark Lord is not out of his own volition. There could be some dark magic or a powerful curse that has been placed on him, which slowly corrupts his mind and makes him act in ways that are similar to Voldemort. For example, he might start to believe that the only way to bring true peace to the wizarding world is through dictatorship, which is a very dark and twisted idea for the usually heroic Harry.
Well, one possible main plot twist could be that Harry's friends turn against him when he starts showing signs of becoming the new Dark Lord. They might initially try to reason with him, but as his power grows, they feel threatened and decide to oppose him.
One major plot twist could be that the Dark Lord has a hidden agenda that no one expected. Maybe he is using a false identity to deceive the wizarding world while secretly planning something even more devious.
One possible take on a 'Dark Lord Harry Potter' fanfiction could be a story where Harry, instead of following the path of a hero, is influenced by dark forces early on. Maybe he discovers a hidden, dark side of magic that the Hogwarts faculty has been suppressing. This could lead to a completely different power dynamic within the wizarding world.
The new Dark Lord in this fanfiction could be a former Hogwarts student who was bullied and turned to the dark arts for revenge. They could start gathering followers among those who feel disenfranchised in the wizarding world. Their goal might be to rewrite the laws of magic to suit their own dark desires. They would likely oppose Harry Potter and his friends, leading to epic battles and tense stand - offs.
One possible plot twist could be that Harry, under the influence of the dark side, forms an alliance with Bellatrix against the Order of the Phoenix. Maybe he discovers some dark secrets about his parents that lead him to question his previous beliefs and side with her.
Yes, there is one where Dark Energon turns Hogwarts into a dark fortress. All the teachers and students are affected by its dark energy. But then it is revealed that it was all a test by Dumbledore to see how the students would react to extreme danger. It was a really unexpected plot twist.
One possible plot twist could be that the succubus is actually an ally sent by someone to test the Lightning Lord. Another could be that the succubus has a hidden power that can nullify the Lightning Lord's magic. Maybe she has a magical amulet that was not known before.
One plot twist could be that the gun is actually a magical object in disguise. It might have been created by a dark wizard who wanted to introduce an element of Muggle - like violence into the wizarding world. Harry discovers this as he tries to use it and realizes that it has powers beyond what he expected. Another twist could be that the use of the gun makes Harry an instant target for both the wizarding authorities and dark forces. He has to constantly evade capture while trying to figure out why the gun has such a strange allure and power.
In this fanfiction, the plot might show Harry's transformation into a Dark Lord as a result of some major betrayal in the wizarding world. For example, if the Ministry of Magic turned against him or if his friends were seriously harmed by the 'good' side. He could then start to see the power of the dark side as a means to exact revenge and reshape the wizarding world according to his own vision. He might recruit former Death Eaters or create his own dark followers.
One possibility is that Harry would be trained in dark magic from a young age. He might grow up believing in the Dark Lord's ideology, which would put him at odds with his friends from the original story. For example, he could be a formidable opponent to Hermione and Ron when they eventually cross paths.
The plot might involve the dark lord's daughter being raised in secrecy. When she discovers her true identity, she decides to use her knowledge of the dark side to actually help the wizarding world. She could start by providing inside information to Harry and his friends about hidden Death Eater lairs or secret dark spells. Along the way, she has to deal with the distrust of others in the wizarding community.