He could have to take a long time to recover, which might make him feel frustrated and impatient. It could also lead to him doubting his abilities as an Auror for a while.
Well, he might be unable to perform his duties on the ship for a while. His friends would surely be worried sick and would probably do everything they could to nurse him back to health. Maybe Annabeth would take charge of his care, using her wisdom to find the best way to heal him.
Well, he could have been captured by dark wizards who were lying in wait. Maybe they had a powerful spell or device that could subdue him. Another possibility is that he got lost in some kind of magical maze or dimension that he accidentally stumbled into during the mission.
His friends would react in a very concerned and protective way. Hermione would use her intelligence to find the best solutions for his recovery. She might also try to figure out what went wrong on the mission to prevent it from happening again. Ron would be there for Harry no matter what, showing his loyalty. Ginny, being Harry's love interest in many fanfictions, would be extremely emotional. She would be a strong presence by his side, making sure he has everything he needs. The rest of his friends would also come together, forming a support network around Harry, sharing memories and positive thoughts to help him through the tough time of recovery.
One possibility could be that he's facing a very powerful dark wizard. Maybe this wizard has some new and unknown dark magic. Harry tries his best to fight but is ultimately overpowered. His friends back at the Ministry are left in shock and grief, and the wizarding world has to deal with the loss of their hero.
He might not be able to spread as much joy. If Jack is hurt, his powers could be weakened. So, the children in his area may start to feel less happy and more afraid, as his presence and ability to create positive wintery magic is reduced.
One possibility could be Harry facing a new dark wizard threat that the Ministry is trying to keep under wraps. As an Auror, he stumbles upon some clues and has to work in secrecy to figure out what's going on before it's too late.
Well, in certain fanfictions, Naruto getting hurt during the bell test can change the dynamic of the team. For example, Sakura could start to see Naruto in a new light, perhaps realizing his determination more deeply. It might also lead to Naruto having to recover for a while, during which time he could have some self - reflection about his skills and how to improve without overexerting himself.
Hermione would be a great ally. With her vast knowledge of magic and her logical thinking, she could help Harry solve complex cases. Ron could also be an ally, using his loyalty and his own skills in combat and magic. Neville might be another one, having grown into a confident and powerful wizard, he could bring his unique skills in herbology and his courage to the Auror department to support Harry.
A new dark wizard who has emerged from the shadows, someone who idolized Voldemort and is trying to pick up where he left off. This antagonist could be using new and more insidious magic that Harry has to figure out how to combat as an Auror.
He could be exploring an old, abandoned building and fall through a rotten floorboard.