One common theme is Matt's internal struggle with his pain. Since he's hurt, it often explores how he copes with his physical and emotional pain while still being Daredevil. Another theme is his relationships, like his friendship with Foggy or his romantic interests. How they react to his hurt state and support him is often a big part of the stories.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). It has a large collection of Daredevil fanfics. Just search for 'Daredevil Matt Hurt' and you'll get a list of relevant stories. Another option is FanFiction.net, though the tagging system there might require a bit more digging to find exactly what you're looking for.
In a fanfic, when the Avengers find out Matt is blind, it could lead to a whole new dynamic within the group. They would start to see Matt in a different light. Some might underestimate him at first, but as they see him in action, they'd realize his blindness doesn't hold him back. His heightened senses would amaze them. For instance, his ability to 'hear' the layout of a room or sense an enemy's approach. This new knowledge would also make the Avengers more protective of Matt in dangerous situations, and they might even learn from him how to rely more on their other senses too.
In many 'Batman Beyond' fanfictions where Dana finds out, it could be about her finding out Bruce Wayne is Batman. Maybe she stumbles upon some evidence in the Batcave or notices some similarities in Terry's behavior to Bruce. For example, she might notice Terry's fighting style is similar to what she's heard about Batman's. It could also be that she discovers some secret technology related to Batman that leads her to the truth.
When the Avengers find out Matt is blind, the team dynamics would shift significantly. Firstly, there would be a new level of respect for Matt's capabilities. His ability to fight crime despite his blindness would inspire the others. Secondly, the Avengers would likely re - evaluate their own skills and how they rely so much on sight. This could lead to them training to improve their other senses. Thirdly, in terms of group cohesion, Matt's situation would bring the team closer as they work together to support him and make him an integral part of the team. There would be a sense of unity in helping Matt thrive within the group and also in learning from his unique skills.