Yes, there could be. In some Harry Potter fanfictions, authors might explore the use of black magic in unique ways. A character squinting could be a sign of them concentrating on a black magic spell or perhaps they're under the influence of some dark force related to black magic. It adds an element of mystery and danger to the story.
Often, there's the theme of temptation. The character who is squinting might be tempted by the power of black magic. It could also be a theme of corruption. As they delve deeper into black magic, shown perhaps by their squinting concentration, they start to become corrupted. Additionally, there could be a theme of mystery, with the squinting adding to the air of mystery around the black magic they are involved in.
In many fanfictions, Harry Potter squinting at Voldemort could be a sign of intense focus. It might be that Harry is trying to read Voldemort's next move, or perhaps he's looking for some sign of weakness. For example, in some stories, Harry's squinting could be related to his newfound magical abilities that he's using to analyze Voldemort's magic signature.
One possible fanfiction could be that Harry Potter is kidnapped by a dark wizard who has some strange power that makes Harry squint. Maybe this wizard is trying to use Harry's unique connection to Voldemort for some dark ritual. Harry has to use his wits and the few spells he can manage while squinting to try and escape.
It might also indicate a newfound curiosity. Fanfiction often takes characters in different directions. Harry could be squinting at Malfoy because he's starting to see a different side of him. Maybe he's noticed something that makes him think Malfoy isn't all bad, and the squint is his way of trying to understand this new Malfoy better.
It could mean a fan - made story (fanfiction) where Harry Potter is looking closely or suspiciously at a snake. Maybe in this fanfiction, the snake has some special significance, like being related to Slytherin or having some kind of magical power that Harry is trying to figure out by squinting at it.
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.
He could be squinting because he's trying to read Shacklebolt's expression carefully. Harry has been through a lot and has learned to be cautious. Maybe he's looking for any sign of deception or unease in Shacklebolt's face.
It could be that Harry has noticed some strange behavior from Malfoy. For instance, Malfoy might be acting secretively around certain areas of Hogwarts. Harry's squinting is his way of observing Malfoy closely to find out what he's hiding.
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.