In 'Danny Phantom Hurt at School' fanfiction, he might be physically hurt during gym class. For example, if there's a malfunctioning piece of equipment or a bully tries to cause him harm during a sports activity. Also, Danny could be emotionally hurt. Say, a teacher wrongly accuses him of something in front of the whole class, which makes him feel isolated and sad.
One possible scenario could be Danny getting bullied at school. Maybe some of the other students find out about his ghost powers and they target him out of fear or jealousy. Another could be that he gets injured during a ghost attack that takes place on school grounds while he's trying to protect his classmates.
Perhaps in the fanfiction, Danny is betrayed by a new ally he trusted. This new character could have joined Danny in his fight against evil ghosts, but in reality, they were working for a more powerful and evil ghost all along. They might use Danny's trust to learn about his weaknesses and then expose him to danger, leaving Danny feeling hurt and alone, having to reevaluate who he can trust in the future.
One possible scenario could be Danny getting injured during a fight with a powerful ghost. Maybe he underestimated the ghost's new power and got hit by a strong energy blast that left him with a serious injury.
One possible scenario could be that Sam betrays Danny's secret identity to someone he doesn't trust, like a ghost hunter. Maybe she does it out of jealousy if Danny starts getting closer to another character.
Even some of the school faculty could be responsible in a sense. For instance, a strict teacher who doesn't understand Danny's situation might push him too hard during detention or some other punishment, which could lead to an accidental injury. Or a science teacher's experiment could go wrong and Danny could get caught in the crossfire.
In some fanfictions, it could happen during a moment of vulnerability. For example, if Sam gets hurt while they're on an adventure, and Danny is really worried about her. As she recovers, Danny realizes how much she means to him and they share a kiss. Or maybe they get stuck in a ghost - created alternate dimension where they think they might not get out. In that desperate situation, they confess their feelings and kiss for the first time.
One possible reason could be that Maddie discovers Danny's secret identity and realizes she has been wrong about him all along. So, she decides to help him out of guilt.
One scenario could be when Danny is in a fight with a villain who has heat - based powers. The intense heat generated by the villain could be too much for Danny to handle, causing him pain and weakening his powers. Another might be if he's trapped in a place with extreme heat, like a factory furnace in the Ghost Zone, and he struggles to escape while the heat takes a toll on him.
One possible plotline could be that Danny gets into a fight with a new and extremely powerful ghost. This ghost has some sort of unique power that can cause severe harm to Danny, like a draining ability that saps his energy and leaves him severely injured. He then has to struggle to hide his condition from his friends and family while trying to find a way to defeat the ghost.
In some fanfictions, a massage could be part of a spa day for the characters. For example, Sam, Tucker, and Danny could all go to a ghost - friendly spa (in a fan - made concept) and there could be humorous situations during the massages. Maybe Danny's powers go a bit haywire during the relaxation process. This type of scenario is great for adding some light - heartedness to the story.
One idea is that Danny is hurt by a ghostly weapon that has some sort of curse on it. The curse slowly drains his energy and makes him weaker over time. His friends try to find a way to break the curse while Danny has to fight his own fading strength. Another idea could be that Danny gets injured while trying to protect someone he loves, like his sister Jazz. This could lead to some emotional moments between them as she tries to help him heal.