One interesting plot could be about a common enemy that forces Naruto, the Justice League and the Teen Titans to team up. They have to overcome their differences in fighting styles and values to defeat this powerful foe. Another plot might be a competition between the three groups to see who can solve a mystery or complete a mission first, which would lead to a lot of rivalries and interesting interactions.
Some members might be shocked. Wonder Woman, for instance, who respects Batman's skills and tenacity, would likely be very disappointed. She might try to persuade him to stay, emphasizing the importance of his presence in the team. Superman, on the other hand, might initially be understanding, as he knows Batman has his own way of doing things. But he would also be concerned about the power vacuum that Batman's departure would create. Aquaman might be more indifferent, thinking that Batman was always an outsider to some extent, with his focus mainly on land - based issues.
In a Naruto x Justice League vs Teen Titans fanfiction battle, Naruto could potentially hold his own against the Justice League. His shadow clone jutsu could confuse Superman for a moment, and his rasengan might be able to do some damage. But the Justice League has Batman's strategic mind. The Teen Titans, on the other hand, have Raven's magic and Beast Boy's shape - shifting. It would be a chaotic and exciting battle where the outcome would be determined by who uses their abilities more effectively at the right time.
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.
Some of them might be amused. They could find the different takes on their characters and stories quite entertaining. For example, Superman might chuckle at a fanfic that has him in a comical situation.
The Teen Titans would react with a combination of fear and courage. Starfire, being from another planet, might have some knowledge about the invaders which could be useful. But she'd also be worried about her new home, Earth. Cyborg would probably be excited to take on the new technology of the aliens, seeing it as a challenge to improve his own. Raven, on the other hand, would be more cautious and try to sense any dark motives behind the invasion.
The Justice League as a whole would have a diverse range of reactions. Some members like the Flash would be all for it, seeing it as a fun exploration of Batman. Others like Wonder Woman might use it as a way to understand how the public perceives Batman's role in the League. And then there are those like Aquaman who might just shrug it off unless it directly affects his interests. The fanfiction could also potentially create some internal discussions within the League about how they are all portrayed in the public's imagination.
Some of them might laugh. They would see the creative and sometimes out - there ideas that fans come up with in the fanfiction. For example, if there's a fanfic where Oliver Queen teams up with a really strange character from the Arrowverse, it could be quite humorous to them.
Another theme is teamwork. They have to work together to face various challenges, so the fanfic shows how they combine their different skills and powers. For instance, Cyborg's technological expertise with the Young Justice's strategic planning skills.
A really interesting fanfiction is 'The New Generation of Titans and Young Justice'. This one focuses on the next - generation characters from both series. It shows how they grow and develop, and how they deal with the legacies left by their predecessors. It's a great read for those interested in character development within the fanfiction world.