In this fanfiction, the pregnancy could be a result of a long - awaited and carefully planned event for Neville and Hannah. They could have a whole journey of going to magical healers for prenatal care. As Hannah's pregnancy progresses, they could face some challenges. Maybe there are some dark forces (like remnants of Death Eaters or some new dark magic threat) that try to harm Hannah or the unborn baby because Neville is a well - known and respected wizard. But with the help of their friends and their own courage, they overcome these threats and look forward to the birth of their child.
One possible plot could be that Neville and Hannah discover they are pregnant unexpectedly. They might initially be filled with a mix of shock and joy. Then they could start preparing for the baby, like Neville reading all the books on parenting he can find in Hogwarts' library (assuming a Harry Potter - related fanfic). They would also share the news with their friends, who would be excited and offer support.