It could also be that she was kidnapped because of a prophecy. Similar to the way Harry Potter was targeted because of the prophecy about him, there might be a prophecy in this fanfiction about Hermione that made her a target. The kidnappers might believe that by controlling her, they can either prevent or ensure the fulfillment of the prophecy.
Another motive could be related to her family. Maybe there was some sort of blood feud or an old grudge against the Grangers. The kidnappers could have thought that by taking Hermione, they could get revenge on her family. In some fanfictions, there are secret magical families that have long - standing rivalries, and Hermione's kidnapping could be part of that.
One possible motive could be power. In some fanfictions, there might be dark wizards or witches who believe that Hermione, being a very intelligent and magically gifted child even from a young age, could be used to their advantage. They might think that they can control her magic or use her knowledge for their evil plans, like finding ancient magical artifacts or unlocking powerful spells that are otherwise inaccessible.
In these fanfictions, a common motive for Hermione's kidnapping could be her unique knowledge. She is known for her extensive reading and understanding of magic. Some villains might want to use that knowledge for their own gain. For example, they could be looking to uncover ancient and powerful magic that Hermione has studied. Regarding the adoption part, it might be a way for those who kidnap her to control her future. They could think that by 'adopting' her, they can shape her into someone who serves their interests better. It could also be related to a prophecy. If there is a prophecy that involves Hermione in some way, certain groups might kidnap her to either prevent the prophecy from coming true or to make it come true in a way that benefits them.
Another reason might be revenge. There could be a character who has a grudge against Inuyasha or someone close to him. So, they kidnap him to make him suffer or to use him as bait to draw out his friends. For example, if there was a demon whose family was slain by Inuyasha in the past, they might kidnap him for revenge.
Well, it might be that the kidnapper has some sort of medical need that they think Kaoru can fulfill. Since she's a nurse, they could be desperate for medical attention that they can't get through legal means. Or perhaps there's a villain in the fanfiction who just wants to create chaos in the hospital by taking one of its nurses, and Kaoru happened to be the unlucky one.
One possible motive could be ransom. Maybe someone wants a large sum of money from Philip's family or friends. Another could be revenge. Perhaps Philip has unknowingly wronged someone in the fanfiction world, and this is their way of getting back at him.
Maybe Rowle is under the orders of a more powerful dark wizard. In the world of Harry Potter, there are always those higher - ups in the dark side who might want Hermione for her knowledge of magic, especially things like ancient spells and magic theory. So Rowle could be tasked with kidnapping her for that purpose.
One possible motive could be Bellatrix's loyalty to Voldemort. She might think that by kidnapping Hermione, she can get information about Harry Potter and the Order of the Phoenix. Hermione is known to be very intelligent and Bellatrix could believe she has valuable knowledge. For example, Hermione might know the location of Potter or the Order's plans against Voldemort.
One possible motive could be to use Hermione as a bargaining chip against Harry Potter. Since Hermione is his close friend, the kidnappers might think they can force Harry to do something, like give up a powerful magical item or valuable information.
Perhaps it's about love in a twisted way. Sebastian might be obsessed with Clary and think that by kidnapping her, he can make her his. In some fanfictions, characters with a warped sense of love do extreme things like this. He could also be trying to use Clary as a pawn in a larger scheme against the Shadowhunters. By having her in his control, he can manipulate the situation to his advantage.
One possible motive could be misinformation. Maybe Bucky was misled to believe the OC was a threat to someone he cares about. So, he kidnapped the OC to prevent them from causing harm.