The Akatsuki members, if any are still around, would have diverse reactions. Some might see it as a weakness in Pein, while others might be curious about how this new family dynamic could change the balance of power in the shinobi world. Hinata would be shyly supportive of Sakura. She would understand the importance of love and family, and she would hope that Sakura finds happiness, even if she's a bit intimidated by Pein's past actions.
Sakura would be worried sick. She'd try to figure out what happened to Naruto to make him act this way. She might try to talk to him, use her medical ninjutsu to check if he's under some kind of genjutsu or has some other problem. She'd be very vocal about her concerns and would try to get the other villagers to help bring Naruto back to his normal self.
Sakura would probably be very shocked and disappointed in Naruto. She has always had deep feelings for him. Kakashi might be more level - headed, trying to figure out how to handle the situation from a strategic and diplomatic point of view.
One plot idea could be that Pein and Sakura are brought together by some strange and unexpected circumstances in the Naruto universe. Maybe there's a powerful jutsu gone wrong that binds their fates. As Sakura discovers she's pregnant, she has to deal with the reactions of her friends in Konoha, while Pein, being from a different background, has his own internal struggles about fatherhood and his place in this new situation.
The Akatsuki members, if they were to encounter Naruto in this state, would have different reactions. Some might see it as an opportunity to target him when he's vulnerable. However, others like Pain, who has his own beliefs about the cycle of pain and suffering, might be a bit more conflicted. He might see Naruto's unborn child as a symbol of a new beginning or just another target. And the other Konoha ninjas, especially the younger ones, would look up to Naruto even more. His pregnancy and time travel situation would make him seem even more of an enigma and a source of inspiration as he's facing such unique challenges.
Sasuke would be extremely suspicious. He has always seen Naruto as his rival and a symbol of the village's hope. If Naruto starts acting like Pein, Sasuke would think it's some kind of trick at first. He might even be ready to fight Naruto to figure out what's really going on.
Sakura and Pein are the central characters for sure. Sakura, who has to come to terms with her newfound family connection. Pein, who may have some hidden motives regarding his daughter. Additionally, characters from the Akatsuki organization that Pein is associated with could also play significant roles in the fanfiction.
Jaime could be torn between his loyalty to his family (if we consider the complex family dynamics in the original story) and his new - found responsibility towards Sansa and the unborn child. He might try to find a way to make things right in his own way. Sansa would start to think about how this affects her political standing and her relationships with other characters. She may seek out allies who can help her through this difficult time, all while dealing with the emotional turmoil of being pregnant in such strange circumstances.
Sakura might be initially shocked and a bit jealous, but she would probably come around to support Naruto as a friend. Kakashi would be more of a calm and collected figure, offering advice on how to handle the situation both as a ninja and as an expecting father. Sasuke, on the other hand, might be indifferent at first but later show some concern for Naruto's well - being in this new situation.
Sakura might be completely shocked at first. She might freeze for a moment, not believing what's happening. Then she could start crying tears of joy and say yes immediately.
She might be heartbroken. Sakura could initially be in shock and then fall into a deep sadness. She may blame herself for Naruto's leaving, thinking that she could have done something differently.