Perhaps Harry joins Voldemort because he believes he can change him from the inside. In this fanfiction, Draco could be the one who initially tries to stop Harry but then realizes that Harry's plan might actually work. They then form an unlikely alliance to bring down Voldemort's more evil plans while Harry is still pretending to be on Voldemort's side.
One possible plotline could be that Harry, after being abused, feels a sense of desperation and a lack of support from the good side. He might be lured by Voldemort's power and the false promises of a new order where he won't be abused. Voldemort could manipulate Harry by showing him a different way of life, perhaps one where he has more control and respect.
In some versions of this type of fanfiction, there could be a time - travel element. Harry travels back in time and ends up getting involved with a younger Voldemort. He sees potential in Voldemort that he believes can be redirected for good, but instead, he gets drawn into Voldemort's dark plans. As a result, he begins to work with Voldemort against the very people he once called friends and allies.
In this fan fiction, the plot could involve Harry's abuse leading him to question his previous beliefs. Voldemort, being a powerful figure, might take advantage of Harry's vulnerability. The 'romance' could be a complex web of power dynamics and emotional manipulation. For example, Voldemort might use his charm and knowledge to draw Harry closer, and Harry, in his state of confusion and hurt from the abuse, might be swayed into believing that there is something more to their relationship than just power - seeking.
In such fanfiction, a common plotline is that Harry's decision to join Voldemort creates a power shift. He might use his status as the 'Boy Who Lived' to undermine Dumbledore's reputation further. Since many in the wizarding world had put their faith in Harry, his joining Voldemort could lead to widespread panic and confusion. Harry could also start to recruit other disillusioned wizards to Voldemort's cause, using his own charm and the false narrative that Voldemort is actually a liberator of the wizarding world from the old, restrictive ways.
Maybe Harry joins Voldemort because he discovers some dark secrets about the so - called good side in the wizarding world. He might think that Voldemort's way of ruling could bring a new order that is more just in his eyes. However, he soon realizes that Voldemort's true nature is far more cruel than he expected, leading to a conflict within himself.
In this fanfiction, Harry joining Voldemort could be a catalyst for Draco to re - evaluate his own beliefs. As they are both in Voldemort's orbit, they are forced to rely on each other. Draco might find himself protecting Harry from the more extreme Death Eaters, and through these shared experiences, their relationship could grow from animosity to something more complex and perhaps even romantic.
One possible plotline could be that Harry is tricked by Voldemort. Voldemort might use some powerful dark magic or false promises to make Harry believe that joining him is the right thing to do. For example, Voldemort could claim to have a way to end all the bloodshed in the wizarding world if Harry helps him.
Well, in many Drarry fanfictions where Draco joins the Order, there's a plotline about him being a double agent. He pretends to still be on the side of the Death Eaters while actually working for the Order. This creates a lot of suspense and danger. Another common one is that Draco joins the Order because he realizes that Voldemort's ideology is wrong and he wants to fight for a better future. His relationship with Harry then evolves as they share common goals. There are also plotlines where Draco's joining the Order causes a rift within the wizarding world, with some pure - blood families seeing it as a betrayal, and this adds more conflict and drama to the story.
Perhaps Voldemort discovers a long - lost family secret of Harry's that gives him leverage. For example, he might find out that there is a curse on Harry's family that only he can break, but only if Harry joins him. Or Voldemort could be using some form of mind - control device that was created by an ancient dark wizard, which he uses on Harry to make him a part of his ranks.
One possible plotline could be Harry being held captive by Voldemort in a way that's like a pet. Voldemort might use Harry to show his power over the Boy Who Lived. Another could be that Harry has some sort of magic that makes Voldemort keep him as a pet instead of killing him immediately.