Another possibility is a group of rogue students who have fallen under the influence of a dark magic artifact. They might attack Hermione because she was trying to stop them from using the artifact for evil purposes.
It could be Death Eaters who see Hermione as a threat to their new plans. Since she's very intelligent and has been involved in many battles against the dark side, they might target her to send a message to the Order of the Phoenix.
Maybe it's a new, previously unknown dark wizard or witch who wants to make a name for themselves by taking out one of the most famous witches at Hogwarts. They attack Hermione when she's alone, thinking they can easily get away with it.
Harry and Ron are the most obvious choices. They've always been there for Hermione in the original series, so it would make sense for them to be the ones to find her and try to save her life. They would use their combined magical skills and knowledge to fight off any remaining threats and get her to safety.
It could be rogue ninjas from other villages. These ninjas might be jealous of Naruto's power or they could be on a mission to steal some of his unique abilities. For instance, some might want to take the Nine - Tails' chakra from him.
It could be a group of out - of - town bounty hunters. They might have heard about Nicole's reputation as a tough cop and see her as a valuable target to bring in for some kind of reward. Maybe they are working for a shadowy figure who wants Nicole out of the way so they can take over the town's law enforcement.
In some fanfictions, Hermione could be attacked by a new, unknown magical creature that has been unleashed by an evil force. She might be left for dead because the attacker believes she is already dead or simply doesn't care. It could also be that she is betrayed by someone she trusts, like a fellow Hogwarts student who has turned to the dark side, and they set her up to be attacked.
One possible plotline could be that Hermione was attacked by a group of dark wizards while on a solo mission. They might have been after some knowledge she possessed. After the attack, she could be found by a mysterious figure who nurses her back to health and together they seek revenge.
It could be rival students from Hogwarts who are jealous of their magical abilities. There are always some students who might be envious and could turn to the dark side of magic to try and harm them.
The Titans might not be completely defeated. Some of their followers could be plotting against Percy. They think that by getting rid of him, they can start a new uprising against the gods. So, they leave him in a dangerous situation where they believe he will surely die.
One possible reason could be a misunderstanding. Maybe Hermione thought Snape was involved in some dark plot against her friends. In the wizarding world, there are often secrets and deceptions, and if she got some false information, it could lead her to take such drastic action.
Perhaps there was some sort of dark influence or mind - control at play. An enemy might have manipulated Kakashi's mind in such a way that he believed Naruto was a threat and thus left him for dead, not realizing his true self.
One possible reason could be a misunderstanding. Maybe they were misled by false information or an enemy's trickery that made them think Naruto was a threat at that moment. Another reason might be extreme pressure or a life - or - death situation where they thought sacrificing Naruto was the only way to save the rest of the team or complete a crucial mission.