She could also use her magic skills. Maybe she could perform a powerful spell that she has been secretly preparing for such a situation. Hermione is a very talented witch, and she might be able to create a distraction or a shield long enough to get away from Bellatrix.
Hermione could use her intelligence to outwit Bellatrix. She might pretend to be compliant and gradually gain Bellatrix's trust, all the while looking for an opportunity to escape. For instance, she could trick Bellatrix into thinking she has some important information that can only be retrieved in a certain location, and then make a run for it when they get there.
Another way would be if her friends come to rescue her. Harry and Ron could track her down using their skills and knowledge. Once they arrive, they could work together to overpower Bellatrix and free Hermione. The power of their friendship and combined magical abilities would be a great asset in this situation.
Hermione might try to escape by using her intelligence to analyze Tom Riddle's lair. She could look for any weaknesses in the magical protections he has set up. For instance, if there are any magical runes, she could try to decipher them and find a way to disable them. She might also use her knowledge of potions to create a distraction. Maybe she could brew a potion that creates a thick fog or some other effect that would allow her to slip away unnoticed.
Luna Lovegood might be involved. She could provide some unique magical items or knowledge to Hermione that helps in the fight against Bellatrix. Also, Severus Snape could be a character in the fanfiction. His complex relationship with both the Order of the Phoenix and the Death Eaters could add an interesting layer to the story. Maybe he has some information that Hermione needs to defeat Bellatrix.
The Gryffindor house would be in an uproar. Her friends and classmates would be desperate to do something. Neville, for example, might step up more than ever, given his own growth in courage. They would likely start by informing the teachers, like McGonagall, who would then take the matter to Dumbledore's Army.
Perhaps Bellatrix kidnapped Hermione to use her as bait to lure Harry. Bellatrix has always been extremely loyal to Voldemort and might think that by having Hermione, she can draw Harry out into the open. Hermione, being the intelligent witch she is, could try to outwit Bellatrix while in captivity, maybe by finding a way to send messages to her friends or even by trying to escape on her own.
She might use her intelligence and magic skills. For example, she could create a distraction using a spell like 'Confundo' on her captors and then make a run for it. Hermione is known for her quick thinking, so she could also find a loophole in the security measures set by the Order.
Living with Bellatrix would be a terrifying experience for Hermione. However, she would rely on her wits. She would probably keep her Gryffindor courage in check and act more like a Slytherin, being cunning and sly. She might start to understand Bellatrix's insecurities and use them to her benefit. For instance, if Bellatrix is insecure about her standing among the Death Eaters, Hermione could offer advice that seems helpful but actually undermines Bellatrix's loyalty to Voldemort. And she would constantly be on the lookout for any signs of kindness or humanity in Bellatrix, hoping to use it as a way to change the situation.
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.
At first, Hermione would probably be in shock and defiance. But she'd quickly start to strategize. She'd use her vast knowledge of magic to protect herself from Bellatrix's potential outbursts.
They might start by gathering information. Harry could use his invisibility cloak to sneak around and eavesdrop on potential suspects. Ron would probably try to contact his brothers who have connections in different parts of the wizarding world for any leads.
Well, in some fanfictions, it can start as a power play. Bellatrix, being the dark and powerful character she is, uses the physical position as a way to assert dominance over Hermione. But then it can lead to a more complex relationship where Hermione, instead of being completely submissive, challenges Bellatrix, and this can be the start of a strange sort of mutual understanding or even a twisted form of attraction.