In some fanfictions, Batman might sacrifice himself to save the Justice League from an all - powerful enemy. For example, facing a threat that can only be stopped by using a dangerous self - destruct device that Batman activates while the others escape.
Another scenario could be that Batman is poisoned or infected with a deadly virus. He hides his condition for a while as he tries to find a cure, but eventually, it's too late, and he succumbs to the illness. His death could then be a catalyst for the Justice League to become more vigilant about threats that target their members individually.
Maybe Batman gets mortally wounded in a battle against a new, extremely powerful villain. The League tries their best to save him, but his injuries are too severe, and he dies in the arms of his comrades, like Superman or Wonder Woman. This could lead to the League having to deal with the grief and also face new challenges without Batman's strategic mind.
In many Justice League fanfictions where Batman dies, it could lead to a complete shift in the team dynamics. For example, the League might become more reckless without Batman's strategic mind. Superman could struggle with the loss, perhaps blaming himself for not being able to protect Batman. The other members like Wonder Woman would have to step up in terms of leadership and planning. It could also open the door for new characters to emerge in the fanfiction's storyline, trying to fill the void left by Batman.
The Flash might initially be in denial. He's used to Batman always having a plan and his death would be a huge shock. He would then turn his speed into a tool for investigation, trying to find out exactly what happened. Green Lantern could feel a sense of loss but also be spurred into action, using his ring to try and prevent future tragedies like Batman's death. He might create constructs in Batman's memory to inspire the team.
Another scenario could be that Robin is caught in a trap set by a super - villain. The trap could be a time - bomb - like situation where he has to choose between saving himself or a large number of civilians. He chooses the latter and gets killed in the process, leaving his friends in the Young Justice team to avenge his death.
One possible scenario could be that Wally sacrifices himself to save the team from a powerful enemy. Maybe he uses his super speed to create a distraction and gets caught in an explosion. Another could be that he's affected by some sort of dark magic during a mission and it slowly drains his life force until he passes away. Or perhaps he takes on a time - related mission where he has to correct a major timeline disruption but the cost is his own life.
Another scenario could be when Batman is under the influence of some sort of dark magic or mind - control. He then uses his skills and knowledge against the League in ways they never expected. His sudden change in behavior and the fact that they have to fight a friend can be really frightening. Also, Batman might create a false apocalyptic scenario where the Justice League fails miserably. He shows them their weaknesses and how those could lead to the destruction of the world. This makes them question their abilities and scares them into re - evaluating their roles.
In the fanfiction, perhaps Artemis decides to take on a more solo approach to her vigilantism. She may feel that with her mom gone, she can't rely on anyone else in the same way. This could lead to conflict within the Young Justice team as they try to bring her back into the fold. Also, she might start investigating the circumstances around her mom's death more closely, uncovering secrets that put her in danger.
The Justice League's reaction in fanfiction when Batman dies can vary greatly. Superman might become more withdrawn, feeling like he failed as a friend and protector. Wonder Woman could be the one to try and hold the team together, using her strength and wisdom. The Flash might struggle with guilt, thinking he could have been faster to save Batman. Each member would have their own internal conflict and way of dealing with the loss, which could lead to some interesting character development in the fanfiction.
Perhaps a member of the Justice League, accidentally. For instance, during a fight where powers go out of control. Let's say Flash runs too fast and accidentally knocks Batman into a sharp object, causing a fatal injury. This would create a huge moral dilemma within the League.
Another storyline might involve Batman leaving because of a personal crisis. For example, he discovers something dark about his past that makes him question his place in the Justice League. He might think that he's a liability to the team and decide to leave to protect them.
One scenario could be Naruto using his clones to distract the Justice League while he sneaks up on Superman and uses a powerful jutsu. Another could be the Justice League trying to find Naruto's weakness, like his connection to the nine - tailed fox, and Naruto having to defend himself against their attacks. Maybe Batman tries to analyze Naruto's fighting style and come up with a plan to defeat him.