What could be the reasons for John getting injured in a fanfiction?

One reason could be her inexperience in combat. Despite her growth, she is still not as skilled as some of her companions. For example, when facing a new type of demon she might misjudge its attack pattern and get injured. Another reason could be her curiosity. If she wanders off alone into an unknown area, she could easily step into a trap or encounter a hidden danger, like a poisonous plant or a concealed pitfall.

One reason could be his own clumsiness. Maybe Peter is always in a rush and not paying enough attention to his surroundings. For example, he could be running down the stairs while looking at his phone and trip, resulting in an injury.

Another reason could be an accident. In some fanfictions, the setting might be more of a daily - life scenario with a twist. Perhaps Usagi is distracted while walking and trips over something, resulting in an injury. This can add a touch of realism to the otherwise fantastical world she lives in.

Another possibility is that it's a rogue Shadowhunter. There are always those in the community who don't agree with the way things are going. If Clary's actions or ideas are seen as too radical, this rogue Shadowhunter might try to stop her by injuring her. This could also lead to a story about Clary trying to understand the motives of this attacker and potentially reform them.

He could be exploring an old, abandoned building and fall through a rotten floorboard.

In fanfiction, Katniss might get sick due to exposure to new and dangerous toxins in the post - Hunger Games world. Maybe she's exploring uncharted areas and breathes in something harmful.

In fanfiction, she could be injured during a battle against dark wizards. Maybe she was caught off - guard while trying to protect her friends.

One reason could be that he was being a bit too adventurous. He might have tried to climb a tree that was too high or unstable for him. As he reached for a higher branch, he lost his balance and fell, getting hurt in the process. Also, bad weather conditions can play a role. If it had rained recently and the ground was slippery, Chris could have slipped and fallen while walking in the park.

Well, in some fanfictions, it could be because of a curse or a jinx that was unknowingly placed on him before he arrived at the Burrow. The Burrow is not always a completely safe place, and with all the comings and goings of wizards and witches, someone with ill intentions could have targeted Harry. Also, he might have eaten something that didn't agree with him. The Weasley family's cooking, while delicious most of the time, could have used some ingredients that Harry's body wasn't used to.

One reason could be ChiChi's overbearing nature. She is often very strict about Goku's training and how he spends his time. In fanfiction, this could be exaggerated to the point where Goku finally gets fed up. For example, if she constantly nags him about not doing enough chores around the house instead of training, it might push Goku to his limit.