A group of thieves could be the kidnappers. They were planning on robbing Daria's house but found her there instead. They take her with them to avoid being caught and in the rush, her glasses are lost. They might keep her hostage until they figure out what to do with her, all the while Daria is trying to figure out how to escape and get her glasses back.
Perhaps it's a jealous rival. Maybe in the world of this fanfiction, there's some sort of competition, like for a job or a love interest. And this rival decided to kidnap Felicity to get her out of the way.
Another possibility is that a mysterious stranger comes to her rescue. This stranger might have been secretly following her kidnapper. He or she could fight off the kidnapper and then take Felicity to a safe place. And then they help her find a new pair of 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.
The Avengers would be extremely concerned. Captain America would immediately start strategizing a rescue mission. Thor might be angry and ready to use his strength to find her. Black Widow would use her espionage skills to gather information on the kidnappers. And Iron Man would likely use his technology to track any possible leads, all while being aware that Darcy without her glasses might be in a more difficult situation.
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.
A plot twist could be that Harry's kidnapping and loss of glasses is the result of a time - travel mishap. A future version of himself (or someone else) accidentally causes the present - day Harry to be kidnapped and lose his glasses. The future version is trying to change the course of events for the better but ends up creating chaos in the present. Harry, without his glasses, has to figure out what's going on and how to fix the time - line while also escaping from his kidnapper. Another twist could be that the kidnapper is actually an undercover Auror gone rogue who is using Harry as a bait to draw out a much larger and more dangerous criminal organization. Harry's glasses are lost in the process, and he has to figure out who to trust among his captors.
Felicity could develop a deeper sense of empathy. Being kidnapped and losing her glasses makes her experience a kind of helplessness. This could make her more understanding of others who are in difficult situations. Also, she may become more street - smart. She has to quickly adapt to the situation without the aid of her glasses, so she might pick up on little details that she previously overlooked, which could change her overall perception and how she approaches life.
In a fanfiction setting, the girl who tripped and lost her glasses could be a magical being in disguise. When she tripped, it could be a sign that her powers were about to be revealed. For example, she might be a fairy whose glasses were enchanted to hide her true identity. Losing them could lead to a series of adventures as she tries to retrieve them before the wrong people find out who she really is.
Well, perhaps Daria, being drunk and without her glasses, stumbles into an Avengers gathering by mistake. She could start blabbering some drunken wisdom that the Avengers find both amusing and oddly profound. Maybe she gives Captain America some off - the - wall advice on modern society, all while the other Avengers are trying to figure out who this strange, inebriated girl is.