He could misidentify people. Maybe he mistakes a Slytherin for a Gryffindor and gets into an awkward situation. It would be a humorous scenario where he has to quickly correct himself.
Perhaps in the fanfiction, Harry discovers a new spell or a magical item that can temporarily enhance his vision without glasses. But there could be a catch, like it only works for a short time or has some side - effects. This would lead to a whole adventure of him trying to find a more permanent solution while also dealing with the normal challenges in the wizarding world.
Well, he might be stumbling around a lot. Without his glasses, Harry's vision is really poor. He could easily bump into things in the tunnel, like hidden magical creatures or even some sort of magical traps. Maybe he'd be using his other senses more, like his sense of hearing to detect any approaching danger.
Well, without his glasses, Harry might rely more on his other senses. His magical instincts could be heightened. When dealing with the Snatchers, this could mean he'd be able to sense their dark magic more acutely. He could use this to his advantage, perhaps by using magic to disrupt their search for him. And the Snatchers might underestimate him because they think he's at a disadvantage without his glasses.
He might end up in a place where he can't see clearly without his glasses and struggles to find his way. For example, he could be in a dark forest where he stumbles around, trying to figure out where he is and how to get back. Without his glasses, his magical abilities might also be affected in some way, like his spell - casting accuracy.
He would probably be very disoriented. Without his glasses, Harry's vision is extremely poor. In the dungeon, which is likely to be dark and full of various obstacles, he might stumble around, bump into things, and have a hard time finding his way out. This could lead to some dangerous situations as he may accidentally trigger traps or run into unfriendly creatures.
In the fanfiction, if Harry Potter's glasses were confiscated, he would be at a huge disadvantage. His ability to observe his surroundings, which is crucial in the wizarding world full of hidden passages and magical creatures, would be severely hampered. Without his glasses, he might not be able to recognize friends or foes quickly. Also, during Quidditch, he wouldn't be able to see the Snitch clearly, and his team could lose the game.
He could misidentify something important. For example, he might think an approaching friendly ship is an enemy vessel because he can't see clearly. This could lead to a lot of chaos and misunderstanding among his comrades on the ship.
One possible plot for a 'Harry Potter in prison without glasses' fanfiction could be that Voldemort or his followers have managed to frame Harry for a serious crime. In prison, without his glasses, Harry is constantly disoriented. He has to learn to adapt quickly. There could be a new character, perhaps a sympathetic prison guard or a fellow inmate who helps him get by. Harry could also discover some hidden magic within the prison walls that he can only access because he is in this vulnerable state without his glasses. This new magic could be the key to his escape and also to defeating Voldemort's plans in the long run.
Well, perhaps in this fanfiction, Harry could be imprisoned by some dark wizards. Without his glasses, he'd be at a great disadvantage, relying more on his other senses and magical instincts. Maybe he uses his Parseltongue ability to communicate with a snake in the cell to help him escape.
In a 'Harry Potter without glasses brawl' fanfiction, it could start during a Quidditch match. Without his glasses, Harry can't see clearly. He thinks an opposing team's player is trying to cheat in a really aggressive way and he jumps into a fight mid - air. This could lead to a huge brawl between the two teams. And the Ministry of Magic might get involved later to sort out the mess.