In some fanfictions, Jane Foster could play a role. If she's around Asgard at the time, being a scientist, she might have some knowledge or technology that could be used to treat Loki's wounds. Also, Valkyrie could be a helper. She's a fierce warrior and has a sense of honor. She might see Loki's injury as a chance to prove her worth or as a debt she needs to repay if Loki had previously helped her in some way. And of course, Frigga, if she were still alive in the fanfiction, would be a great source of comfort and healing magic for Loki.
One likely character would be her closest friend. This person would be by her side immediately, providing emotional support and maybe even some basic first - aid if they are able. They would stay with her throughout her recovery process, being a source of comfort.
Alex is very likely to be one of the first to help Kara. As her sister, she has a deep bond with Kara and would do anything to protect her. Alex has medical training and combat skills, so she can both treat Kara's injuries and defend her if needed. Another character would be Winn. He is a tech - genius and could use his knowledge to create something to help Kara heal faster or to find a way to counter whatever caused her injury. Also, J'onn J'onzz, with his shape - shifting and telepathic abilities, could be a great asset in protecting Kara while she's injured and in helping her recover mentally as well as physically.
Erak might be an unexpected character to help. Despite his rough exterior, he has a sense of honor. If he happened to be in the area when Will gets hurt, he could offer his ship as a means of quick transport to a place where Will can be treated. Also, the apprentices that Will has trained. They would look up to him and would be eager to repay his kindness. They could run errands, gather herbs for medicine, or keep watch while Will recovers.
Definitely his friends from Camp Half - Blood. Percy Jackson, for instance, would be likely to be involved. He might be the one to find Nico when he's hurt or be part of the group that's trying to rescue him. Annabeth could also be involved as she is often in the thick of things and would use her strategic mind to help Nico when he's injured. Hazel, being his sister, is very likely to be there. She would be extremely worried and do whatever she can to heal or protect him.
Well, Sasuke could be involved. He might be the one who finds Sakura when she's hurt and has to deal with his feelings for her while trying to get her help. Naruto is also a likely character. He could be devastated by Sakura's injury and vow to get revenge on whoever caused it.
Hermione would definitely be one of the first to help. She's extremely intelligent and well - read in magic, so she'd quickly start looking for spells or potions to heal Harry. She'd also stay by his side to comfort him and keep his spirits up.
Katara would be a likely character to help Toph recover. Katara is a waterbender and has healing abilities. She would use her skills to tend to Toph's injuries, whether they are physical wounds or internal damage from overusing her earthbending. Another one could be Aang. He's the Avatar and has a deep connection with all the elements. He might use his spiritual knowledge to help Toph heal faster, maybe by finding a special place for her to rest and regain her strength.
Nobara Kugisaki and Megumi Fushiguro could also be among those who help. Nobara is a strong - willed and capable sorceress. She would be concerned about Nanami's well - being and use her skills to assist him. Megumi, being a calm and intelligent sorcerer, would likely come up with a plan to rescue or heal Nanami. They all share a sense of comradeship within the Jujutsu Kaisen world.
Dr. Bruce Banner could play an important role. His scientific knowledge could be used to analyze Captain America's condition and come up with solutions. In some fanfictions, he might even find a way to enhance Captain America's healing abilities. Also, Thor, if he's around, could use his Asgardian magic or knowledge to help in the healing process, perhaps by bringing some rare Asgardian herb or elixir that has healing properties.
Kakashi Sensei could also be involved. He is Naruto's teacher and mentor. If Naruto gets hurt during a mission that Kakashi is leading, Kakashi would surely be there. He might feel responsible for Naruto's injury and would do everything he can to protect him further and get him to safety. And then there's Pain. In some fanfics, Pain could be the one who attacks Naruto and causes him to get hurt, especially if the fanfic is centered around the events related to Pain's invasion.