The fanfiction could explore a scenario where Harry's glasses are taken away as a way to break his spirit. Voldemort, having Harry as his pet, might want to completely subdue him. Without his glasses, Harry has to navigate a blurry world. This could lead to some interesting interactions with other characters. For example, Hermione might try to find a magical way to restore Harry's vision or at least give him some form of sight assistance without glasses. Ron, on the other hand, could be conflicted about whether to help Harry escape Voldemort's clutches or if he should follow Voldemort's orders as well since Harry seems so different without his glasses.
Maybe in this fanfiction, Voldemort has a change of heart after making Harry his pet. Without his glasses, Harry appears more helpless, and this could stir some long - forgotten emotions in Voldemort. He starts to see Harry not just as an enemy but as someone he can manipulate in a different way. He could try to groom Harry to be on his side, using a combination of threats and false kindness. Harry, on the other hand, is constantly thinking of how to turn the tables and get back to his friends and the fight against the Dark Lord.
In some fanfictions, Voldemort's pet might be used as a symbol of his power and evil. Harry's glasses, on the other hand, are an iconic part of his character. The combination could be used to create a unique plot. For example, Voldemort's pet might steal Harry's glasses to disrupt his vision and thus his ability to fight. It could also be a more symbolic connection, like the pet representing Voldemort's hold over Harry's life, and the glasses being a symbol of Harry's identity that Voldemort wants to break.
Harry would likely be defiant at first. Even without his glasses, he has his inner strength. He would probably try to resist Voldemort's every command and look for opportunities to escape or fight back.
One possible plotline could be that Voldemort's pet somehow steals Harry's glasses as a way to taunt him. This could lead to Harry going on a quest to retrieve them, facing various dark magic obstacles along the way.
It could be that Voldemort's pet Harry is actually a form of psychological warfare for Voldemort. He wants to break Harry's spirit completely. However, Harry uses this situation to his advantage. He befriends some of the dark creatures that Voldemort has around his lair, and with their help, he manages to create chaos and confusion, which in turn gives the Order of the Phoenix an opportunity to strike at Voldemort.
It could be that the pet is magically attracted to the glasses. Maybe the glasses have a certain charm or power that the pet senses, and it tries to steal them to bring back to Voldemort. For example, if the glasses can see through certain dark magic disguises, Voldemort would want to get his hands on them through his pet.
The pet could try to break Harry's glasses. Since Voldemort hates Harry, his pet might be programmed or trained to destroy things that are important to Harry. The glasses are a very visible and important part of Harry.
Perhaps in this fanfiction, Harry is in a cage as part of a magical experiment. Some rogue wizards are trying to study how a wizard's magic is affected without their usual aids, like Harry's glasses. In the cage, Harry discovers new aspects of his magic that he didn't know before. He could start to manipulate the magical energy around him in different ways, even without clear vision, and eventually break free from the cage and confront those who put him there.
In this fanfiction, Harry without his glasses could be in a situation where he is forced to rely on his friends more when dealing with Horcruxes. His vision impairment without glasses makes it difficult for him to be as independent as he used to be. So, Hermione and Ron play a more crucial role. For example, when they are searching for a Horcrux in a dark and dangerous place, Harry has to trust their descriptions completely. And as they progress, Harry discovers that the Horcruxes are affecting his vision in a magical way, and he has to find a way to break this spell while still trying to destroy the Horcruxes.
One possible plot could be that Harry, without his glasses and drunk, stumbles around Hogwarts in a daze. He might accidentally end up in a restricted area, like the Forbidden Forest. Maybe he has some misadventures with the magical creatures there, all while being in a drunken state and unable to see clearly. His friends would then have to go and find him.