The Hidden Leaf villagers would be shocked. They see Akatsuki as the enemy, so they would think Naruto and Sasuke have betrayed them. Kakashi would probably be very concerned and try to find out their reasons. Sakura would be heartbroken and might even try to go after them to bring them back. As for the Akatsuki members themselves, some might be suspicious of Naruto and Sasuke's motives at first, while others might see it as an opportunity to use their power for Akatsuki's goals.
In this type of fanfic, Sasuke's motivation to protect Naruto could be his realization of their deep - rooted bond. Maybe he has had a change of heart after all their past encounters. Sasuke could use his Sharingan to foresee any danger coming Naruto's way from the Akatsuki members. He'd be like a shadow, always there but not fully noticed by the Akatsuki, making sure Naruto stays safe.
In fanfics, the relationship between Naruto, Sasuke, Sakura and Akatsuki can be extremely diverse. Naruto often represents the ideal of never - giving - up. Sasuke is the brooding, complex character. Sakura can be a strong - willed female character. Akatsuki, on the other hand, is usually portrayed as the antagonists. Fanfic writers may create various scenarios. For example, they might write about how Naruto tries to redeem members of Akatsuki, or how Sasuke's path intersects with Akatsuki's goals in ways different from the original story. And Sakura could play a role in either helping or hindering these interactions.
The Akatsuki members themselves would have mixed reactions. Some, like Itachi (if he were still alive in the fanfic), might see Naruto as a potential asset but also a threat to their long - term goals. Kisame might be amused by Naruto's presence and see him as a new source of entertainment. Meanwhile, the Leaf Village elders would be outraged. They would see Naruto as a traitor and start devising plans to either bring him back or eliminate him.
Naruto in fanfic might be shown as even more heroic when facing Akatsuki, like single - handedly taking on multiple members. Sasuke could be more of an anti - hero, having some secret alliance with Akatsuki for a time. Sakura is often made into a more powerful ninja than in the original, so she can better deal with Akatsuki threats. Akatsuki members are sometimes given more backstories and sympathetic traits in fanfic.
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.
Sasuke would probably be very guarded at first. He's not used to dealing with something so innocent and vulnerable. He might be suspicious of the baby's presence and think it's some sort of trap.
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.
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.
Sasuke would be furious. He's always been protective of Naruto in his own way. He would immediately start looking for her, using all his skills and resources. He might even go on a rampage if he thought Naruto was in serious danger.