One possible plot could be that a dark wizard kidnaps Harry Potter in order to steal his powers. In the chaos of the abduction, Harry loses his glasses. Without his glasses, he has trouble seeing clearly which adds to his vulnerability. The wizard might be working for Voldemort or could be a new enemy. His friends Hermione and Ron would then embark on a quest to rescue him. They would face many challenges along the way, like getting past dark magic traps and finding the location where Harry is being held captive.
In this fanfiction, Harry Potter's kidnapping might be part of a bigger conspiracy. A group of rogue wizards who oppose the Ministry of Magic could be behind it. They take Harry and make sure he loses his glasses to disorient him. As for the plot, Harry could discover that they want to use him as a bargaining chip to gain control over Hogwarts. His friends start to search for him, but they also have to deal with the Ministry's interference as the Ministry doesn't believe their theory at first. Eventually, they manage to find some clues that lead them to Harry's location and a big showdown between the good and the bad wizards takes place.
One possible plot twist could be that without his glasses, Harry has a hard time recognizing his captors. It might turn out that they are people he thought he could trust, like some seemingly friendly Hufflepuffs who are actually under the Imperius Curse. This would add an element of betrayal and confusion to the story.
Perhaps in the fanfiction, Harry is kidnapped by a powerful magical creature that has a vendetta against wizards. When it grabs Harry, his glasses are knocked off. The creature takes him to its underground den. Harry, without his glasses, is at a great disadvantage as he can't see well. But he remembers the magic within him. He tries to communicate with the creature using Parseltongue (if it's a snake - like creature). He hopes to either convince it to let him go or at least find his glasses so he can better defend himself and find a way back to Hogwarts.
One possible plot twist could be that without his glasses, Harry has trouble recognizing his captors or his surroundings clearly. This could lead to some miscommunications or misunderstandings. For example, he might mistake a friendly wizard trying to rescue him for another captor. Another twist could be that the kidnappers took his glasses to specifically weaken him, as he is so used to seeing the magical world clearly with them. They could be using it as a psychological tactic to make him feel more vulnerable and off - balance.
Maybe it's a jealous student from Hogwarts. Someone who is envious of Harry's fame and power. This student has been studying dark magic in secret and decides to kidnap Harry to prove that they are better. They take his glasses to humiliate him as well. They might think that without his glasses, Harry is just an ordinary wizard and they can easily overpower him.
One possible plot could be that while kidnapped, Harry's lost glasses become a crucial element for his escape. Maybe the kidnappers don't realize the magical properties of the glasses and Harry uses a spell that is activated only when his glasses are in a certain state. For example, he could have a spell on them that when they are broken in a specific way, it sends a signal to his friends at Hogwarts.
A plot twist could be that the place where the character is kidnapped has some hidden objects or clues that can only be found without glasses. For example, there might be a hidden message written in a way that is visible only to blurry vision. Also, the character might be kidnapped by someone they thought was a friend, and without their glasses, they initially mistake the kidnapper for someone else, which adds to the mystery and confusion. When they finally realize who it is, it's a big shock.
Perhaps Felicity has a hidden power that is only activated when she has her glasses. Without them, she has to find an alternative way to fight back against her kidnappers. This could lead to her developing new skills or alliances within the story.
A fanfiction could start with Harry's glasses being stolen by a mischievous house - elf. Harry starts to squint to see in his classes, which causes some problems. For instance, in Potions class, he misreads the instructions and creates a minor explosion. He spends the day trying to find the house - elf and his glasses. Along the way, he meets some other characters who help him in unexpected ways. By the end of the day, he gets his glasses back and has learned a valuable lesson about not taking his eyesight for granted.
It could be a group of rogue Death Eaters who think that kidnapping Harry would bring them back into Voldemort's good graces. They might take his glasses as a way to humiliate him, seeing Harry as the symbol of their defeat. They underestimate Harry's resourcefulness even without his glasses.
One possible plot could be that Daria is kidnapped by a group who mistake her for someone else. In the chaos of the kidnapping, her glasses are lost. As she's held captive, she has to rely on her wits more than ever without her glasses to see clearly. She might start to analyze her captors' behavior and motives, trying to find a way to escape. Maybe she uses her sharp tongue and intelligence to outwit them, all while dealing with the inconvenience of not having her glasses.