Naruto would probably be really angry at first. He's a free - spirited person who doesn't like being forced into things. So he'd likely try to fight back right away, yelling at Sasuke about what he's doing.
The ninja community's reaction would be quite mixed. Some, like Naruto's close friends such as Shikamaru and Kakashi, would be supportive. They would likely offer their protection and assistance to Naruto during his pregnancy. However, there would also be those who are more traditional and might view Naruto's pregnancy as a weakness or something that goes against the norms of the ninja world. They could try to isolate Naruto or even oppose Sasuke's relationship with him because of it.
On the other hand, Sasuke could be worried. He may think that Naruto is in some kind of trouble or danger. Given their history and the care they have for each other in the SasuNaru dynamic, Sasuke's concern could lead him to be more protective. He might start investigating the situation on his own to figure out why Naruto is hiding his face and ensure his safety.
Sasuke might also be angry. Angry at the situation, angry at whoever or whatever caused Naruto's amnesia. His anger could fuel his determination to find a cure. He would push himself and Naruto harder in training, hoping that it would jog Naruto's memory, all while trying to hide his true feelings of worry and fear for Naruto's well - being.
He could feel a sense of guilt. Sasuke might think that his actions or their relationship issues pushed Naruto to leave. He may then set out to find Naruto, not only to bring him back but also to resolve their long - standing issues. For example, if there were unspoken words or unresolved fights between them, Sasuke would see this as an opportunity to set things right.
In these fanfictions, Naruto's character is often based on his canonical self, which is full of energy and a bit of a goofball at times. Menma, on the other hand, may be a bit more mysterious or have a different backstory that shapes his character. But they can both have a strong sense of justice. Naruto has always fought for what he believes is right in the main series, and Menma can be written to have a similar moral compass in fanfiction. They may also both experience growth throughout the story, learning from their mistakes and becoming better ninja.
Sakura could be really interesting. She might be confused at first by Menma's presence, thinking he's some kind of impostor Naruto. But as she gets to know him, she could see his unique qualities and might even develop a friendly rivalry with him. Another interesting character could be Kakashi. He would be observing Naruto and Menma's interactions closely, maybe even giving them some special training to help them work together better.
One great 'Menma and Sakura' fanfiction is 'The Unseen Bond'. It beautifully explores the relationship between the two characters. The story takes them on an adventure where they discover hidden powers within themselves and also deepens their friendship in a very heartwarming way.
Some popular Sasunaru fanfictions often include ones that focus on their unique bond and growth. 'The Road to Redemption' might be among the best as it delves deep into Sasuke's return and how Naruto helps him reintegrate. Another could be 'A Bond Beyond Comprehension' which shows their emotional connection in different challenging situations. And 'Friendship and More' explores the development of their relationship from friendship to something deeper in a really engaging way.