One possible plot could be that the baby has unique magical abilities. Since Harry has his own set of powerful magic and Fleur is part Veela, their baby might inherit a combination. Maybe the baby can communicate with magical creatures in a special way, leading to adventures where they all have to protect the baby from those who might want to use its powers for evil.
Well, it could inherit some of Harry's skills like Parseltongue perhaps, given its connection to Slytherin's heritage through Harry. And from Fleur, it might have an affinity for water magic since she has Veela heritage. Maybe the baby could also have strong defensive magic abilities as both Harry and Fleur have shown great courage and the ability to defend themselves in tough situations.
In raising their baby, Harry and Fleur would have to deal with the public eye. Given Harry's fame and Fleur's allure, their baby would be somewhat of a celebrity in the wizarding world. They would need to protect the baby from too much media attention. At home, they would introduce the baby to different magical spells and charms gradually. Harry could teach the baby some of the more practical defensive spells he knows, while Fleur could share her knowledge of Veela - related magic, like how to use her charm in a positive and non - manipulative way.
Well, one way it could occur in fanfiction is if there's a magical artifact involved. Suppose there's an ancient magical object that has the power to create life when two people with strong magic, like Hermione and Fleur, interact with it. Another possibility is that a powerful magical being decides to play a trick on them and creates this baby situation as a way to teach them a lesson or to set off a series of events in the fanfiction world.
In fanfiction, if Harry Potter and Fleur had a baby, the child might inherit some amazing magical abilities. Harry has his own set of skills like his proficiency in Defense Against the Dark Arts, and Fleur is part Veela, so the baby could potentially have some Veela charm and powerful magic from both sides. Maybe the story could focus on how the wizarding world reacts to this unique child, whether with excitement or suspicion.
They would probably have a close relationship. As siblings, they'd likely look out for each other. Fleur might be protective of Harry, and Harry would respect and admire his sister. Since Fleur is older and more experienced in the wizarding world in some ways, she could be like a mentor to Harry at times.
Often, Luna Lovegood can be found in such fanfictions. Her unique and dreamy nature could bring a different dynamic to the harem. Neville Longbottom might also be involved in some way, perhaps as a friend who supports the harem and helps them out in times of need. There could also be some foreign exchange students or magical creatures in human form that end up in the harem for various reasons.
Well, at first, their relationship might be a bit of a shock to those around them in the wizarding world. But having a baby would force them to really come together. Harry would have to get used to Fleur's Veela - influenced emotions and Fleur would have to understand Harry's sometimes reckless Gryffindor nature. They would become more patient with each other as they raise their child. There would be shared responsibilities, from teaching the baby magic to instilling good values. Their relationship would be one of mutual growth as they face the new chapter of their lives as parents.
They would likely become more protective of each other. With a baby in the picture, they know that they need to be a united front. Harry, who has always been a fighter, would be even more determined to keep his family safe. Fleur, being a proud and strong - willed woman, would also step up her game in protecting her new family.