In another plotline, Timmy and Trixie are exploring an old, abandoned magical castle. They accidentally trigger a trap. Timmy pushes Trixie out of the way of a falling boulder or some other dangerous object. After getting hurt, Trixie feels guilty and vows to stay by his side until he recovers. She uses her wits to find a way to get them out of the castle and to a place where Timmy can be healed.
One possible plotline could be that Timmy and Trixie are in a magical forest when a group of dark fairies attacks. Timmy uses his fairy - godparent powers to shield Trixie from their harmful spells, getting hurt in the process. Trixie then has to find a way to help him, like searching for a special healing flower.
Maybe they are at a school event that gets invaded by some sort of magical creatures. Timmy steps in front of Trixie to protect her from their attacks. As he's hurt, Trixie realizes her true feelings for him and decides to fight alongside him to defeat the creatures. Then she takes him to get medical help from the school nurse, who has some knowledge of magical injuries.
In a plotline, the enemy might be after Vivi for some political reason. Luffy steps in without hesitation. He gets hurt but his determination to protect Vivi doesn't waver. This could lead to the Straw Hat crew coming together in a new way to face the threat. For example, Nami could use her navigation skills to find a safe haven where Luffy can recover while the others hold off the enemy.
The theme of heroism is also present. Timmy becomes the hero in these stories, even if he gets hurt. His actions inspire Trixie to be braver herself. And there could be a theme of redemption, especially if in the normal story arc Trixie has been mean to Timmy, but now she has a chance to make it up to him as he's injured because of her.
One common plotline could be Naruto facing a powerful enemy alone to safeguard Sakura. For example, in a fight against a rogue ninja who has a vendetta against Sakura's medical skills, Naruto jumps in front of an attack meant for her. This could lead to him getting seriously injured and Sakura having to use her medical ninjutsu to save him while also realizing her true feelings for Naruto.
Maybe they are in a forest filled with dangerous magical creatures. A giant snake - like creature lunges at Annabeth. Percy quickly moves in front of her and the creature bites his leg. In another situation, they are in a magical maze. There are walls closing in on them and spikes starting to protrude from the sides. Percy pushes Annabeth out of the way of a spike that was about to impale her, but he gets scratched all over his body. And they could be in a fight against a powerful sorcerer. The sorcerer casts a spell of dark energy towards Annabeth, and Percy uses his own power to try and block it. However, some of the dark energy seeps through and causes internal damage to Percy.
In a story, there could be a situation where a magical curse is spreading. Beast Boy, seeing Raven in the path of the curse, uses his own body to block it. As a result, he is infected by the curse which starts to harm him physically and mentally. Raven then embarks on a journey to find a cure, all the while taking care of Beast Boy and their relationship deepens through this difficult time.
One possible fanfiction plot could be during a village invasion. Naruto, with his unwavering sense of justice and his growing feelings for Hinata, shields her from an enemy's attack. He might get seriously injured, which then spurs Hinata to tap into her own hidden power to defend him in return. This kind of story can explore their bond deeper and show how they support each other in tough times.
There could be a fanfiction where Naruto and Ino are exploring an ancient ruin. Unbeknownst to them, there are traps everywhere. When a huge boulder starts rolling towards Ino, Naruto pushes her out of the way. He gets crushed under the boulder's edge. Ino is desperate to save him. She manages to find some herbs in the ruin that have healing properties and uses her medical knowledge to treat Naruto's injuries. Meanwhile, Naruto's willpower also helps him in his recovery.
One possible scenario could be that Shinra and Iris are in a battle against some powerful demons. Shinra tries his best to shield Iris from the demons' attacks. As he does so, he gets seriously injured but still manages to hold off the demons long enough for backup to arrive. Iris is deeply moved by his selfless act and vows to become stronger to protect him in the future.
In another scenario, Naruto and Hinata are exploring an ancient ruin when traps are triggered. A large boulder is about to crush Hinata, and Naruto uses his body to stop it. He gets injured badly. Hinata then uses her skills in medical ninjutsu that she has been secretly practicing to treat Naruto's wounds as they wait for help to arrive.
One possible plotline could be that Harry gets hurt during a Quidditch match. Maybe a Bludger hits him hard and he has to deal with a serious injury like a broken bone. He then has to struggle with not being able to play for a while and the fear of not being as good when he recovers.