They could describe the way his eyes narrow, almost as if he's trying to force his vision to focus. For example, 'Harry squinted, his green eyes becoming slits as he strained to see without his glasses. The world around him was a blur of colors and shapes.'
The writer can also focus on how it affects his overall appearance. 'Without his glasses, Harry's face looked different. His squinting made him seem more vulnerable, like a lost child. His brows were furrowed in concentration as he tried to make out the details of the room.' This not only describes the physical act of squinting but also gives an emotional undertone.
One possible scene could be during a Gryffindor common room party. James Potter has lost his glasses in the chaos of the celebration. He's trying to find his best friend, Sirius. He's squinting as he looks around the room filled with students laughing, dancing, and chatting. The flickering firelight and the moving bodies make it even harder for him to see. He spots what he thinks is Sirius's black hair but as he moves closer, he realizes it's just a girl with long dark hair. His squinting and the resulting misidentifications add a touch of humor to the party scene.
Another way is to contrast his normal, bespectacled self with this new, glaring - without - glasses version. Maybe in the story, his friends are so used to seeing him with glasses that when he glares without them, it has a different impact on them. The writer can use this to create interesting character interactions and development within the fanfiction. For instance, Hermione might be initially shocked but then realize the new level of intensity Harry has reached.
In this fanfiction, Harry might be on a ship escaping from some dark forces. Squinting without his glasses, he has to rely on his other senses more. His friends could be around him, trying to protect him while he struggles to see clearly. This situation could lead to some tense and exciting moments in the story.
One possible fanfiction could be about Harry being wrongly imprisoned in Azkaban. Without his glasses, he has to rely more on his other senses. He might start to discover hidden magical abilities within himself that he didn't know before. Maybe he can sense the Dementors' approach in a different way and find a way to resist their influence without the use of Patronus charm, which could be a really interesting twist in the story.
There once was a drunk girl at a party. Without her glasses, everything was a blur. She squinted, her long lashes almost touching her cheeks. She had a goofy smile on her face as she stumbled around, trying to make sense of the shapes and colors that swirled around her. It was as if she was in a dreamy, tipsy state, and the lack of glasses only added to her disoriented charm.
There could be a fanfiction where Harry is studying in the library with his broken glasses. He's squinting hard to read the old, faded texts. Hermione notices and offers to help him fix his glasses with a spell she's been researching. But Harry refuses at first, wanting to do it on his own. This creates a bit of tension between them, and as they argue, Ron comes in and tries to mediate. It could be a comical and character - driven fanfiction scenario.
In the fanfiction, the nerdy girl is at a science fair. Without her glasses, she's squinting at the complex diagrams and models on display. Her eyes are narrow slits as she attempts to make out the details of a particularly intricate experiment setup. People around her are chatting excitedly about the projects, but she's focused on trying to see clearly.
There might be a fanfiction where Harry Potter is at a Quidditch match without his glasses. He's squinting to try and spot the Snitch. This could lead to some interesting situations, like misidentifying other flying objects as the Snitch at first, and his team having to cover for him while he struggles without his proper vision.
One possible fanfiction could be about Harry having trouble with his glasses after a spell goes wrong. He has to squint constantly to see clearly, and this leads to some comical situations at Hogwarts. For example, he mistakes a cat for a Kneazle during Care of Magical Creatures class.
One possible fanfiction could be that Harry loses his glasses during a Quidditch match. He has to squint to see the Snitch, which leads to some comical near - misses and some very frustrated team - mates. In the end, he manages to find his glasses just in time to catch the Snitch and win the match.