In terms of his relationship with his teachers, some might be more lenient with him. For example, Professor McGonagall might give him extra help or allowances in class because she understands his situation. However, Snape might use it as an excuse to be even more critical, thinking Harry is just being careless with his glasses.
His relationship with Hermione might change. Hermione would probably be more protective and try to help him find a solution to his 'without glasses disorder'. She might also be a bit more bossy as she tries to guide him around since he can't see well.
It could strengthen his relationship with Hermione. Since she's so studious and resourceful, she would be constantly helping him out when he's without his glasses. Ron might make more jokes about it at first but would also be very protective. It might also make Harry more vulnerable in his relationships, as he depends on others more.
When Harry stumbles without his glasses, it could initially disrupt his magical abilities. He may fumble with his wand or mispronounce spells because he's distracted by his lack of clear vision. However, over time, this could force him to become more adaptable. He might learn to use magic in new ways, like using magic to enhance his vision temporarily or using spells that don't require precise aiming. This would make him a more versatile wizard in the long run.
It can make him look more mysterious. People might not recognize him immediately.
Harry Potter could survive in the dungeon without his glasses by relying on his instincts. He has been in many dangerous situations before and has developed a good sense of danger. He could listen intently for any sounds that might indicate danger or a way out. Additionally, he could try to communicate with magical creatures in the dungeon. Some might be friendly and help him. And if there are any magical objects in the dungeon, he could potentially use them to his advantage. For instance, if there is a magical stone that enhances perception, he could use it to'see' better without his glasses.
His character may seem more exposed. The glasses are a sort of shield for him, and without them, he might appear more open. It could also make him seem less like the 'chosen one' at first, as the glasses are a very recognizable part of his look.
One possible plot could be that without his glasses, Harry discovers he has a new magical ability related to his vision. Maybe he can see magical auras more clearly and it helps him in his fight against the dark forces. For example, he can easily detect hidden Death Eaters by the color of their auras.
In this fanfiction scenario, Harry's relationship with Dumbledore could be very interesting. Dumbledore would surely be aware of the significance of Excalibur. He might take Harry under his wing even more, guiding him on how to use the sword's power for good. Harry's relationship with the other Hogwarts students could also change. Some might look up to him even more, while others might fear him because of the great power he now wields.
If Harry is sleepwalking, it might worry his friends. For example, Hermione would probably be very concerned and try to find a way to stop it. This could strengthen their friendship as she devotes time to helping him. Ron, on the other hand, might initially find it funny but then also realize the seriousness. It could also make some of his classmates more curious about him, which could either bring them closer or create some distance depending on how they react to his sleepwalking episodes.
One possibility could be that in this fanfiction, Harry's glasses are some sort of magical anchor. Without them, he might accidentally slip into a different dimension. Maybe he was in the middle of a battle at Hogwarts, his glasses got knocked off, and suddenly he vanished. It could be that the glasses were enchanted by Dumbledore long ago to keep Harry in the 'right' magical space, and without them, he's lost in a sort of limbo.
Well, in some fanfictions, Harry might rely on his other senses more acutely. He could use his sense of hearing to detect movements around him. For example, he might be able to tell if someone is approaching by the sound of their footsteps. His sense of touch could also help him navigate his surroundings, like feeling the walls or furniture to figure out where he is.