Who could be responsible for Harry being badly hurt in 'Harry is badly hurt fanfiction'?

It could be an enemy. For example, a rival in a competition or a villain who has a grudge against Leo.

In the fanfiction, it might be that a mysterious figure is responsible. This person could have a vendetta against Amy's family or the stables she works at. They could set up a trap, like loosening a fence rail that Amy's horse jumps over, causing the horse to stumble and Amy to be thrown and badly injured.

The Riddler could be responsible. He might set up a series of elaborate and deadly traps throughout Gotham. Batman, in his attempt to solve the riddles and stop the traps from harming innocent people, could end up getting caught in one of them and getting hurt badly. For instance, a trap could involve a collapsing building or a room filled with sharp objects.

There are many possibilities. For example, in the 'Harry is badly hurt fanfiction', it could be that there is a malfunction in a magical experiment he's involved in. The magic backfires and causes him great harm. Or, there could be a plot where a new, powerful and evil force has emerged in the wizarding world and targets Harry specifically. During their encounter, Harry is badly hurt while trying to fight back or escape.

One could be 'Jason's Painful Ordeal' where he gets seriously injured in a battle against a powerful new foe. His friends are left to deal with the aftermath, and it shows their grief and determination to save him.

It could be a rogue Death Eater who has been hiding and waiting for the right moment to strike at Harry. They might use some forbidden dark magic to seriously harm him.

To write a great fanfic about Jason being badly hurt, you need to research. Look at how other fanfics handle injuries. For the story, start with a strong opening that shows the moment of injury vividly. Then, develop the plot around his recovery. Include his friends' reactions, like Annabeth's strategic thinking on how to help or Percy's concern. And don't forget to add some internal monologue for Jason to show his pain and determination.

One possible reason for Natsu to return badly hurt in a fanfiction could be a very tough battle. Maybe he faced an extremely powerful enemy that was far beyond his initial expectations. For example, if he encountered a new type of dark mage with some unknown and dangerous magic. This could lead to him getting seriously injured and having to struggle to return.

Maybe Leo is in a fight and gets seriously injured. His friends then have to find a way to save him.

Perhaps in the fanfiction, Amy Fleming is badly hurt during a storm while trying to save one of the horses. She could be struck by a falling branch or something. Then the story might focus on how she overcomes her physical and mental pain with the help of her love for horses and the people around her. For example, her friends could bring her small gifts related to horses to cheer her up during her recovery in the hospital. Also, her family might be by her side constantly, sharing stories about their own experiences with horses to give her strength.