There's a fanfiction called 'Accident at the Ministry'. In this one, Harry accidentally activates a powerful and ancient magic while at the Ministry of Magic. It sets off a chain of events that involve him having to team up with some unlikely allies to fix the mess he's made. The story has great character development and a lot of action.
A really engaging 'Harry Potter accident' fanfiction is 'Potions Mishap'. In it, Harry has an accident in Snape's Potions class. The wrong combination of ingredients creates a potion that gives him the ability to read minds for a short period. This leads to some hilarious and also some quite serious situations as he discovers secrets about his classmates and teachers.
Well, in some 'the love accident' Harry Potter fanfictions, there might be a plot where a character accidentally discovers their true feelings for another during a dangerous adventure in Hogwarts. For example, a side character might find love with a Gryffindor while they are both searching for a hidden magical artifact.
There's a fanfiction where the Time Turner accident causes a time loop. Harry is stuck repeating the same day over and over again. Each time he tries different things to break the loop, and in the process, he discovers new aspects of his friends and the Hogwarts secrets. It's a really unique take on how the Time Turner can go wrong.
In my fanfiction, during a Quidditch practice, Ginny Weasley has an accident. She's flying really high, trying out a new maneuver. But a strong gust of wind blows her off course. She collides with one of the goalposts. Her teammates rush to her side. Luckily, she only has a few bruises. However, it makes her more determined. She spends the next few days training extra hard to improve her skills and avoid such accidents in the future. She becomes an even better player after this incident.
If a player had a serious Quidditch accident, like breaking a leg, the immediate aftermath would be chaos on the pitch. Teammates would rush to their side, and the game would be stopped. The injured player would be taken to the hospital wing. In the days that follow, their team would have to adjust their strategy without them. The player would be in a lot of pain and have to go through a long recovery process. Their friends would visit often, bringing them notes from class and treats from the kitchen.
Characters could survive a cave accident in a Harry Potter fanfiction by relying on their knowledge of magical plants. Maybe there are some Devil's Snare plants in the cave. If they know how to handle them, they can use the plants to their advantage. For example, they can make a rope out of the Devil's Snare to climb out of a deep hole. Also, they can use their wits and the skills they've learned in their classes. If it's a cave filled with dark magic, they can use their Occlumency skills to protect their minds and then find a way to counter the dark magic using spells like Lumos to find hidden passages or exits.
A great fanfiction is one where the Shadowhunters are invited to Hogwarts to teach a special class on combat using their unique weapons. It shows how the Hogwarts students react to their new teachers and their different style of magic. Another one could be about a Shadowhunter who is a secret Potterhead and has to hide his love for the Harry Potter books in the Shadowhunter society.
I'm not sure of a specific one titled exactly like that, but you can try searching on fanfiction.net or Archive of Our Own. Look for tags like 'Harry Potter', 'Malnourishment', and 'Character Struggles'. There are likely some great stories out there that deal with this theme.
One good lazy Harry Potter fanfiction is when Harry gets a magical illness that makes him extremely lethargic. Instead of fighting it, he just goes with it. He spends his days in the Gryffindor common room, half - asleep on the couch, and the other students start taking care of him in a really sweet way. His laziness actually brings the Gryffindors closer together as they all try to make him feel better.
One good Mokuton Harry Potter fanfiction is 'Mokuton Magic at Hogwarts'. It has an interesting plot where the main character discovers they have Mokuton abilities and has to hide it from the teachers at first. Another is 'The Mokuton Wizard', which shows how Mokuton can be used to solve some of the problems in the wizarding world like overgrown areas in the Forbidden Forest.
Some fanfictions might feature a Thunderbird as a guide for a young wizard or witch. In this kind of story, the Thunderbird could lead the protagonist through hidden magical paths or to forgotten magical places. It could be a really immersive read as it combines the mystery of the Thunderbird with the rich tapestry of the Harry Potter universe.