A possible plot could be that Voldemort kidnaps Hermione because he realizes she has a unique understanding of ancient magic. He hopes to use her to unlock the secrets of magic that could make him even more powerful. Hermione, on the other hand, uses her time in captivity to study the dark magic around her, looking for a way to turn it against Voldemort. She also tries to leave hidden clues for her friends to find her.
In one possible plot, Voldemort might kidnap Hermione to use her knowledge of magic against Harry. He could try to force her to reveal secrets about Dumbledore's plans or the location of certain powerful magical artifacts. Hermione, being strong - willed, would resist and try to outwit Voldemort using her intelligence.
A really interesting plot twist might be that Voldemort is being controlled by an even darker force, and Harry has to figure out a way to break that control while being held captive. Or perhaps Harry's friends, thinking he is dead, accidentally start a chain of events that end up helping Harry escape in a very unexpected way. For example, Hermione might cast a spell that was supposed to be for protection but ends up creating a portal right in Voldemort's lair.
She would be terrified at first, but quickly gather her wits. Hermione is very intelligent, so she would likely start observing her surroundings, looking for any possible means of escape or a way to send a signal to her friends.
One possible plot could be that Dumbledore has been possessed by a dark entity. Under its influence, he kidnaps Hermione thinking she has some knowledge or power that the entity wants. Hermione then has to use her wits to try and break Dumbledore free from the possession while also trying to escape.
The plot could take a turn where Zabini is initially seen as the bad guy because of the kidnapping, but in reality, he is trying to protect Hermione from a greater threat. Maybe there's a prophecy that involves Hermione and Zabini, and the kidnappers are trying to stop the prophecy from coming true. Another possible twist is that Hermione's kidnapping leads to a discovery of a long - lost magic that Zabini's family has been searching for. This magic could change the balance of power in the wizarding world, and now Hermione is in the middle of it all.
One way this could develop is that Voldemort sees an opportunity to use Hermione's intelligence for his own gain through this union. He might think that by having Draco marry Hermione, he can control the magical knowledge she has. Draco, on the other hand, might initially resist as he has his own pure - blood ideals. But under Voldemort's pressure, he could be forced into it. Hermione would surely fight against it, using her wits and the support of her friends like Harry and Ron to find a way out of this strange and unwanted situation.
In some fanfictions with this concept, one key plot point could be Hermione's struggle to resist Voldemort's control while secretly trying to undermine his plans. For example, she might use her intelligence to mislead the Death Eaters. Another point could be the internal conflict she faces between her loyalty to her friends and the need to survive in this dark situation. And sometimes, there could be a sub - plot about her trying to find a way to break the enslavement spell or curse that binds her to Voldemort.
Perhaps in this fanfiction, Naruto discovers some ancient magic similar to Voldemort's dark magic. He becomes intrigued by Voldemort's rise to power and starts to study his methods. However, Naruto's friends would be horrified as they see him drifting towards the dark side. Naruto might think he can use Voldemort - like tactics for good, but it's a slippery slope.
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.
One possible plot could be that Aladdin is kidnapped by a powerful sorcerer who wants to use his knowledge of the magic lamp to gain more power. His friends, Jasmine and Genie, then have to embark on a dangerous journey to rescue him. They might face various obstacles along the way, like magical traps and other evil minions.