First, know the 'Harry Potter' lore well. Understand the character of the Dark Lord, his motives, and his powers. Then, come up with a unique plot. It could be something like the Dark Lord travels back in time to change the course of his own defeat. Also, create believable characters to interact with the Dark Lord, whether they are new characters or existing ones from the series.
To write a good 'Harry Potter Dark Lord fanfic', you need to focus on character development. The Dark Lord should be more than just a one - dimensional villain. Maybe show his vulnerability or his internal struggles. For the plot, you can play with different timelines or alternate universes. For instance, what if the Dark Lord won in an alternate reality? How would the wizarding world look like? And don't forget to use vivid descriptions to bring the magical world to life, from the dark and foreboding lairs of the Dark Lord to the bustling halls of Hogwarts.
Another good one could be 'Dark Lord Potter and the Hogwarts of Shadows'. In this fanfic, the dark lord Harry Potter has a different set of relationships with the other characters. The author does an excellent job of building a new Hogwarts environment that's filled with mystery and danger. It really explores the idea of what would happen if Harry took a darker path in a detailed way.
The teachers at Hogwarts, like Dumbledore (if he were still alive in the fanfic), would be deeply concerned. Dumbledore always saw great potential in Harry for good. He would probably try to understand what led Harry to this path and would use all his wisdom and magic to try and turn Harry back. The other teachers would also be on high alert, fearing for the safety of the students and the future of the wizarding world.
I really like 'The Dark Lord's Son: A New Path for Harry'. In this fanfic, Harry is raised by the Dark Lord's followers after Voldemort's victory. It shows a completely different Hogwarts, full of dark magic teachings. The story is full of twists and turns as Harry starts to question the world he's living in.
Well, in 'Dark Lord Harry Potter fanfic', the most obvious change is Harry's alignment. Instead of being the hero, he becomes the villain or at least an anti - hero. This completely flips the moral compass of the story.
I think it's a bad take. In the official Harry Potter lore, Harry has always been on the side of light. He was the one who faced Voldemort, the ultimate dark wizard, multiple times and defeated him. To make Harry a dark wizard in a fanfic completely distorts the well - established character arcs and the overall positive message of the series.
The characters included the male protagonist, Harry Potter, the First Seat of Slytherin, the savior of the Wizarding World, and the only heir to the Potter family. The female protagonist was Cassandra Warley, born Slytherin, the eldest daughter of the Warley family. The female protagonist was Hermione Granger, the future Minister of Magic. "Harry Potter wants to be the Dark Lord" by Hong Chen Ruo Yang. It was a light novel/derivative Doujinshi novel with a system style and magical elements. When Harry Potter was no longer at the mercy of others, everything changed. Snape stared blankly at the results of the Sorting Hat's spit "Potter's in Slytherin!" He couldn't take it anymore. And our infamous Dark Lord, the man who seeks immortality, has barely been resurrected. "Your Reaper Curse is nothing, former Dark Lord." Malfoy: Your ideas are now rubbish to us. A familiar face appeared in front of him, revealing the lightning scar, the wand flashing green against his forehead, and whispered,"Lord Voldemort, your time is long over, Avada Kedavra!" Hermione: "On behalf of the Ministry of Magic, I declare that Lord Voldemort is dead." He had changed the wizarding world! I hope you will like this book.
Well, there are fanfics where the Dark Lord actually has a change of heart in the 'Harry Potter Dark Lord fanfic' genre. It might start with him seeing the error of his ways after experiencing a vision of a desolate future caused by his actions. Some fanfics also explore his relationship with his Death Eaters in a more complex way, showing that not all of them are blindly loyal and there are power struggles within the dark ranks.
One popular 'Harry Potter' fanfic about the next Dark Lord could be 'The Heir of Darkness'. It presents a really interesting scenario where a new dark force rises in the wizarding world long after Voldemort's fall. The character development is quite good, especially of the new 'Dark Lord' - who has motives that are a mix of personal vendetta and a twisted view of the wizarding hierarchy.
In such a fanfic, perhaps Harry Potter is magically manipulated. The Dark Lord could use some powerful dark magic to cloud Harry's judgment. Harry might then start to use his skills and knowledge, which were originally meant for good, to help the Dark Lord's evil plans. For example, he could use his Parseltongue ability to communicate with dark creatures for the Dark Lord's purposes.
The story could take a wild turn. Maybe Harry's descent into darkness is driven by betrayal or a thirst for power, and it leads to a whole new kind of magical conflict.