Well, in a fanfiction, Draco could be a secret admirer of King Arthur's tales. He could start collecting ancient artifacts related to Arthur in the wizarding world. This would lead him on adventures, and he might even form a group similar to the Knights of the Round Table among his Slytherin friends, with their own set of rules based on Arthurian ideals.
One way could be by having Draco find inspiration in King Arthur's code of chivalry. He might strive to be more noble in his actions, like Arthur. For example, he could start treating those he previously looked down on with more respect.
Another way could be through a potion gone wrong. In the wizarding world, potions can have all sorts of strange effects. If Draco was trying to brew a potion for some other purpose, like trying to gain an advantage in a competition or something, and made a mistake in the ingredients or the brewing process, it could result in him being transformed into Hermione. This would force him to experience life from her perspective, which could be a huge character - development opportunity for him.
Draco might admire Arthur's leadership. Arthur led his knights and his kingdom with confidence. Draco, coming from a family with certain expectations of leadership in the wizarding world, could look up to that.
I'm not sure it's a 'popular' concept in a general sense. It might be popular among certain fans who like to explore different takes on Draco's character. Maybe it challenges the traditional view of his pure - blood status in the original story, which could attract those who want to see more complex and alternative interpretations of the wizarding world's blood hierarchy.
Well, one way could be that Draco has some sort of ulterior motive. Maybe he wants to use Harry to bargain with the Order of the Phoenix or the Death Eaters. He might think that having Harry in his custody gives him power. Another possibility is that Draco is actually trying to protect Harry from something he knows is coming, but his methods are extreme. For example, he could have heard of a new dark wizard threat and believes that by kidnapping Harry, he can keep him safe in a secret location.
One way could be through a magic spell gone wrong. Maybe Harry was trying to transform into an Animagus but something went awry and he ended up with the mind of a puppy instead of the intended animal. He'd then have to figure out how to reverse it while dealing with his new puppy - like instincts, like chasing his own tail or getting distracted by squirrels.
In a story where Harry Potter has no emotions, his relationships would be greatly affected. Hermione and Ron might be constantly puzzled by his behavior. For instance, when they celebrate a victory, Harry doesn't show any joy. This could create a lot of tension within the trio. Also, his lack of fear could make him take extremely dangerous risks without hesitation. Maybe he would walk into a room full of Death Eaters without any concern for his safety, just because he doesn't feel the normal human emotions that would stop him.
Yes, it is quite popular in some corners of the fanfiction world. There are many fans who enjoy exploring this alternative relationship. It offers a different take on the characters' dynamics and allows for creative storytelling that goes beyond the original canon. It can also show character growth and a mending of the animosity between them.
In fanfiction, this could be the result of a multiverse concept. Suppose there are infinite parallel universes. In one of these universes, the rules are different and somehow the Malfoy family and Nico's family are connected. Draco and Nico might initially be in disbelief but then gradually come to accept it. Their relationship could be full of tension at first, given Draco's often haughty attitude and Nico's own guarded personality. But as the story progresses, they could start to rely on each other and form a unique bond that is different from the relationships they have in their original storylines.
It could be about Draco Malfoy realizing that the concept of pureblood superiority is wrong. Maybe he meets someone who makes him see that blood status doesn't define a person's worth. For example, he could fall in love with a half - blood or a Muggle - born and through that relationship, he starts to question the pureblood ideology he was brought up with.
Well, it might be due to lack of interest from the writers over time. As the fandom evolves, new characters or storylines might become more popular, causing writers to shift their focus away from Draco Malfoy fanfiction. Also, some fanfiction might disappear if the authors themselves decide to remove it for personal reasons, like they no longer want to be associated with that work or they have rewritten it into something else.