In this type of fanfiction, there could be a plotline where Neville discovers he has some latent magical abilities that are awakened by the situation of getting fem Harry pregnant. He uses these newfound powers to protect her and the unborn child. Meanwhile, fem Harry might be struggling with her own identity as she is now in a situation she never expected. She could be worried about how this will affect her future in the wizarding world, but Neville is there to support her every step of the way.
Well, perhaps in the fanfiction, the pregnancy could be a result of some sort of magical accident. For example, a misfired spell that has unintended consequences. Then, Neville and fem Harry would have to deal with not only the physical changes but also the emotional turmoil. They might seek help from their friends like Hermione and Ron, who could offer different perspectives on how to handle this situation.
Their relationship could develop in a rather complex way. At first, they may be shocked by the pregnancy. But then, as they face the reality together, they find themselves falling in love. Neville could become more protective, and fem Harry could see a side of Neville she never noticed before. They would grow through shared experiences like preparing for the baby's arrival, dealing with family reactions, and facing the wizarding society's judgment.
Well, perhaps there could be a plotline where Loki, being a powerful and complex character, tries to use his magic to ensure the safety of Harry and the unborn child. He could be in conflict with other magical forces that see this as an abomination or a threat to the natural order. And Harry, on the other hand, might be dealing with his own insecurities and fears about becoming a parent at a young age.
In some fanfiction, they could be on a quest to find a hidden magical artifact that was once owned by a great wizard. Along the way, they encounter various magical creatures and overcome obstacles using their combined skills and courage. Neville's knowledge of Herbology and Harry's combat skills would make them a great team. For example, Neville could use his knowledge of plants to create barriers or distractions while Harry battles any dark wizards or dangerous creatures that try to stop them.
One possible plotline could be Harry and Neville teaming up to discover a new spell or magical ability that has been long forgotten in Hogwarts. They might explore the Forbidden Forest together in search of ingredients for a potion related to this discovery.
In this fanfiction, a plotline could center around the cultural differences between Fleur (being part - Veela) and Tonks (a Metamorphmagus). Harry would have to navigate these differences as they raise their children together. There could also be a plotline about the training and upbringing of the children, as they are likely to be very powerful with Harry as their father, and how this will shape the wizarding world in the future.
One interesting plotline could be Neville, who is already good at Herbology, discovers a new way to use plants in potions with Harry's help. This changes the way potions are made at Hogwarts.
One possible plotline could be Vegeta dealing with the physical and emotional changes during pregnancy. He might struggle with his pride while also having to rely on others for support.
Well, a plotline could involve Inuyasha's pregnancy being a result of some magical or otherworldly event. This could lead to a search for a way to reverse it or accept it. Also, his pregnancy might bring out a more nurturing side of his personality that was previously hidden. He could start to bond more with characters like Kagome in a different way as they support him through this strange situation.
One possible plotline could be that Harry and Cho initially struggle with the news. They might face judgment from their friends and the wizarding community. Harry, being the responsible person he is, would likely try to support Cho through the pregnancy. They could also decide to keep it a secret at first to avoid the chaos it would cause at Hogwarts.
One major problem is that it goes against the nature of the relationship between Sirius and Harry in the original 'Harry Potter' series. Their relationship is more of a mentor - mentee or a father - son like bond, not a romantic or sexual one.