Some members like Itachi might be very calm and just observe quietly. He would probably analyze the stories, thinking about how the characters are developed and what the underlying themes are.
Some members might be skeptical at first. For instance, Kakuzu would be worried about how her presence could affect their money - making operations. But others like Itachi might see her as an opportunity to change the Akatsuki from within. He might try to guide her and use her positive energy to sway the group towards a more noble path.
Sakura might be very cautious at first. She's heard about the Akatsuki's bad reputation, so she would keep her distance. For example, if she sees an Akatsuki member lurking around school, she'd probably try to avoid them and alert the proper authorities, like the school security or her ninja mentors if it's in a Naruto - like world with ninja training in high school.
Superman might be a bit amused. He'd see the Naruto characters' struggles and compare them to the challenges he faces in Metropolis. Batman would probably study it like he does any case, trying to figure out the motives of the characters in the fanfiction. Wonder Woman would likely be drawn to the strong female characters in Naruto fanfiction, if there are any.
Naruto could use his shadow clone jutsu to play pranks. For instance, he could make clones that look like the Akatsuki members themselves and have them do really silly things like dance around in circles or sing out - of - tune. The real Akatsuki members would be really confused at first, thinking one of their comrades has gone crazy.
Naruto would probably be initially cautious but also curious. He has a knack for seeing the good in people, so he might try to befriend the Akatsuki sister. Kurenai, on the other hand, would be more guarded. She is a more experienced ninja and would be wary of any Akatsuki member. But she also might see an opportunity to gain intel from the sister.
Batman would be vigilant. He'd probably look into it to see if there's any threat or misinformation in it.
Naruto joining Akatsuki would be a shock to many members. But some like Pain might see potential in him. Pain could view Naruto as a tool to achieve his goals or as a symbol of change within the organization. Naruto would try to convince Pain that there are better ways than destruction. Sakura's relationship with Kakuzu could be interesting. Kakuzu is all about money, and Sakura could use her knowledge of Konoha's economy to bargain with him. This could lead to a complex relationship where they are both trying to outwit each other while also having a certain level of respect for each other's skills.
Batman would probably be more critical. He'd analyze how the fanfiction portrays his detective skills and his relationship with the other members of the Justice League. He might not like it if the stories make him seem too soft or too brutal, as he has a very specific self - image.
Some might be amused, while others could be offended. It depends on how they are depicted in the fanfiction.
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.