Venom could be another one. He has a vendetta against Spiderman, and knowing he's injured, he would likely try to finish him off once and for all. He could lurk in the shadows waiting for the right moment to attack.
Even some of the Gryffindor students might be depicted as taking advantage in certain fanfictions. For instance, if they are jealous of Hermione's success or popularity, they could try to use her for their own self - promotion within the house or at Hogwarts.
Well, one way is to show his physical therapy. Maybe he has to work with a specialized doctor in the fanfiction. For example, he could be doing exercises to regain his strength and agility. This would also be a great opportunity to show his determination, as he pushes through the pain.
His teammates are very likely to help. Kagami, for instance, might push him during rehabilitation exercises in a tough - love kind of way. The other members of Seirin could also offer moral support, like bringing him his favorite snacks or just spending time with him. His coach too could be involved, providing expert advice on how to come back stronger.
Maybe it's a new villain in the fanfiction. Some powerful and evil character who sees Leo as a threat to their plans. This villain could use their unique powers or weapons to harm Leo. For example, a villain with the ability to control electricity could zap Leo and cause internal injuries.
Maybe it's one of his old enemies who has found a new way to attack him. For instance, Vlad could come up with a more devious plan that manages to catch Danny off - guard and injure him. Vlad has always been a formidable foe, and he might use Danny's overconfidence or a moment of weakness against him.
Even some of the antagonists could potentially help Jaune if there is a complex relationship developed in the fanfiction. For example, if an enemy realizes that Jaune's death or continued injury would disrupt some sort of balance, they might step in to heal him, albeit reluctantly.
Sasuke is very likely to be involved. Given their complex relationship, Sasuke could be the one who finds Naruto severely injured and has to make a choice between helping him or leaving him. Another character could be Sakura. As a medic - ninja, she would be the one to try and heal Naruto's severe injuries. Kakashi too might be involved, either as a mentor figure who tries to figure out what happened to Naruto or as someone who has to step in to protect Naruto from further harm while he is injured.
In the fanfiction, it might be a new character introduced specifically for this plot. This new person could be jealous of the Hardy Boys' reputation and wants to harm them. So, they target Joe and cause his injury. Another possibility is that it's an accident caused by a person who didn't mean to harm Joe but was just being careless, like someone working on a construction site near where the Hardy Boys were investigating.
The Hokage at the time, whether it's Tsunade or someone else, would likely get involved. They would allocate resources and ensure that the best medical care is provided. Additionally, some of the older ninja who knew Kakashi since he was young, like Iruka, might offer moral support and assist in any way they can, like gathering information or running errands related to his treatment.
Bobby could also be a key figure. He's like a father figure to the boys and has a wealth of knowledge. He might know of some old remedies or be able to point them in the right direction to find a way to heal Dean. Charlie could also pitch in. She's smart and resourceful and could use her hacking skills to find information related to Dean's injury.