This kind of fanfic is really unique. It might explore how Harry deals with the shock of the situation. He could struggle with the physical and emotional changes that come with pregnancy. Maybe he would initially deny it or be in complete disbelief.
It could be that the pregnancy is a sign of a prophecy coming true in a very unexpected way. In the wizarding world, prophecies often have strange and convoluted ways of manifesting. Harry might discover that this pregnancy is linked to a greater destiny for him and the wizarding world. Maybe the child he's carrying will be a powerful force for good or evil, depending on how things play out. His relationship with Ginny would also be greatly affected. She would have to deal with her own feelings about Harry's situation, and they would need to work together to face this extraordinary event.
In the fanfic 'Malfoy's Revelation', Malfoy is paired with Harry for a project. As they spend time together, Malfoy notices some strange behaviors from Harry, like flinching at sudden movements. After some snooping around, he discovers that Harry has been abused. This new knowledge makes Malfoy more empathetic towards Harry and he tries to help him in his own way, which includes standing up for Harry against some of their mutual enemies at Hogwarts.
He might be overjoyed at first. Castle has always been deeply in love with Beckett, and a baby would be like a new adventure for them. He'd probably start making plans right away, thinking about baby names and how to turn one of the rooms in their place into a nursery.
He would definitely question his identity. He's always seen himself as a male hero, and now this completely changes his self - perception. He might wonder if he can still be the same person who fought Voldemort. His masculinity would be a big part of this identity crisis. He'd be in a situation that goes against the traditional male role in society, both the Muggle and wizarding society. And he'd have to reevaluate what it means to be strong and brave in this new context.
The fanfiction might show Harry re - evaluating his relationships based on this new identity. He may wonder how his identity as a potential parent affects his relationships with Ginny or other love interests. His friends may also view him differently, and he has to figure out if he still fits into the same social circles or if he needs to find new ones.
One interesting plot development could be how Harry deals with the reactions of his friends. For example, Hermione might be initially shocked but then become very supportive, using her vast knowledge to research about this unprecedented situation for a male wizard. Ron, on the other hand, could be more comically bewildered and struggle to come to terms with it.
One possible development is that Sasuke becomes more involved in the village. He realizes he needs to create a stable environment for his family, so he starts to take on more responsibilities in the village.
In some fanfics, Sasuke might initially be shocked. He could then feel a mix of joy and fear. Joy because he's starting a family with Sakura, but fear because of the responsibilities and potential dangers that might come with it.