In this fanfiction, perhaps Henry starts to see the world in a different way as the Dark One. He could be tempted by the power to do things he never thought of before, like using it for revenge on those who wronged him in the past. And then there's the aspect of how the other characters react to his transformation. Some might try to save him, while others might see him as a threat and try to eliminate him.
One interesting plot development could be Henry's internal conflict. On one hand, he has the power of the Dark One which gives him great abilities. But on the other hand, he has his moral compass from before. He may find himself in situations where he has to choose between using the dark power for what seems like the greater good at the time, or sticking to his old values. For example, he might be able to stop a great evil using the dark power, but it would require sacrificing some of his innocence. This kind of internal struggle can lead to a lot of character growth and interesting story arcs.
One possible plot development could be Regina struggling with the newfound dark powers. For example, she might accidentally harm those she cares about, like Henry. Another could be her facing off against other magical beings who sense her new dark presence and either fear or want to use her for their own gains.
Another development could be Regina facing off against other dark forces. Since she is now the Dark One, she might attract the attention of more powerful and ancient evils. They could see her as a threat or a potential ally, leading to some intense battles and power struggles.
In this fanfiction, perhaps Umbridge becomes a dark lady and forms an alliance with other dark forces. She could use her knowledge of the Ministry's inner workings to help them. This might lead to a big conflict where the good guys, like Harry and his friends, have to figure out how to stop her and her new allies. It would be really exciting to see how the characters react to this new, more dangerous Umbridge.
Well, one could be that Xander struggles with his new vampire nature while still trying to protect his friends. He might have to fight against his new bloodlust and find a way to coexist with the Scooby Gang without scaring them off.
There could be other magical beings as well. Maybe the wizard who might know something about the Dark One's power and how to reverse it. Also, Henry's friends like Violet could play a role. They might be initially scared of him but then decide to help him because they believe in the good in him still. And don't forget about Hook, who has experience with dark magic and could either be an ally or an adversary depending on the story's direction.
In some of these fanfictions, Harry might start exploring the dark art of necromancy secretly. He could be driven by a desire to bring back his lost loved ones, like his parents. This often leads to him having to hide his newfound interest from his friends at Hogwarts, creating a lot of internal conflict as he struggles between what he knows is right and his longing for his family.
Often, Harry as a lord may have to deal with the political side of the wizarding world. He might face opposition from the old pure - blood families who don't want a 'half - blood' lord to have so much power. So, there could be a lot of intrigue and power struggles in the story.
In some versions, Harry might struggle with the internal conflict of having the Dark Mark. He could face discrimination from those who believe he has truly turned to the dark side. This could lead to a situation where he has to prove his innocence while also dealing with the newfound power or connection that the Dark Mark might bring.
One interesting plot development could be that Harry uses his new status as master of death to bring back some of the fallen characters, like Sirius Black or Fred Weasley. He might be able to rewrite some of the fates that were sealed during the war.
Well, one possible plot could be that Emma, after being pushed to her limits by the constant threats in her world, decides to embrace the power of the Dark One. She might start off using it for what she believes is the greater good, like protecting her loved ones from a new, more powerful enemy. But as she delves deeper into the dark magic, she starts to lose herself. Her relationships begin to fray as her friends and family see the changes in her. And she has to struggle with the internal battle between her old self and the new, dark self that is emerging.