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.
Well, a lot could happen. Jason Todd's complex personality could add a new dynamic to the Young Justice team. Maybe he'd start off as a bit of an outsider, given his past. He could have some tense moments with the more idealistic members. For example, his methods of dealing with villains might be a bit more extreme compared to the Young Justice crew. But over time, he could grow to respect their way of doing things and they could learn from his street - smart tactics.
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.
He'd probably be confused at first. Naruto is used to being among friends and comrades. But then, his determination would kick in. He'd likely try to talk to them, to understand why they think he's a threat.
Some might be shocked. For instance, Batman is often portrayed in very different ways in fanfiction compared to his 'canon' self. Superman might raise an eyebrow at a fanfic where Batman is overly emotional. Others like the Flash might be really into it, finding the different takes on Batman's character and his adventures exciting.
We could expect a storyline where Jason Todd has to face his own demons while being part of the Young Justice group. His time in the Lazarus Pit and his experiences with death could be explored in relation to the more positive and hopeful environment of Young Justice. There might also be a love - interest - based storyline, perhaps with a Young Justice character who sees the good in him despite his flaws.
Jason Todd's age varies depending on the specific comic storyline and continuity. But generally, he's often depicted as being in his late teens or early twenties.
Batman could become more of an anti - hero. He might start working against the Justice League's interests, thinking that they have wronged him. He would use his skills and resources to expose any flaws in the League's operations and undermine their public image.