Harry could also try to reason with Voldemort. He might remind Voldemort of the prophecies and how killing him might not be in Voldemort's best interest. He could also try to appeal to any bit of humanity that might still be left in Voldemort, although that's a long shot.
A third plot twist could involve a character we least expect coming to Harry's rescue. Perhaps a Slytherin student who has been secretly against Voldemort all along. This student could have some inside knowledge about Voldemort's lair and manages to free Harry, leading to a change in the dynamic between the houses at Hogwarts.
In many such fanfictions, there could be a lot of different scenarios. One possibility is that the wizarding world would be in chaos. Dumbledore might lead a frantic search for baby Harry. Maybe some of the Order of the Phoenix members would try to infiltrate Voldemort's lair to rescue him. It could also be that Voldemort has some strange plan for Harry, like trying to turn him to the dark side from a very young age.
In a fanfic where Voldemort kidnaps Harry, it could lead to a lot of intense situations. Harry might be used as a bait to lure his friends into a trap. Or Voldemort could try to turn Harry to the dark side, using various forms of dark magic and psychological manipulation.
Well, Harry might discover some hidden passageways in Voldemort's lair. Since he has a lot of experience with tricky situations at Hogwarts, he could use his wits to find a way out. Also, he could try to appeal to any shred of humanity left in Voldemort's followers, if there are any, and get them to help him escape.
In some fanfictions, Hermione might use her wits to try and outsmart Voldemort. For example, she could pretend to be on his side while secretly planning an escape or a way to undermine his plans. She's very intelligent, so she could try to find a weakness in Voldemort's defenses or his followers.
In some fanfictions, the focus could shift to Hermione's internal struggle. She might be forced to relive some of her worst memories or face her fears because of Voldemort's dark magic. However, this could also be the moment when she discovers new powers or strengths within herself that she didn't know she had, which she could then use to escape or fight back.
Harry often becomes more conflicted. He has always seen Voldemort as the ultimate evil, but now being mates, he has to re - evaluate his views. He might start to see the humanity in Voldemort, which makes him question his own beliefs and actions in the fight against the Dark Lord. For example, he may hesitate in battles more than before.
Often in fanfiction, their relationship can change drastically. They could end up as allies, which would require both of them to change. Harry would have to see past Voldemort's evil deeds, and Voldemort would have to let go of his hatred for Harry. This exploration of character change makes fanfiction so interesting.
One popular fanfic could be 'The Dark Lord's Captive' where Hermione is kidnapped by Voldemort and she uses her intelligence to outwit him in unexpected ways. Another might be 'Hermione in the Dark Lord's Lair' which focuses on her psychological struggle while being held captive.