Yes, there are likely fanfictions where Harry Potter calls Hermione 'baby'. Fanfiction writers often explore different relationships and character interactions in the Harry Potter universe, and this kind of endearing or unexpected use of language can be a part of their creative interpretations.
Voldemort's remaining followers could be antagonists. They might see the baby as a new threat or a potential weapon. They could try to kidnap the baby to use its power for their own dark purposes.
One possible storyline could be that in the fanfiction, Harry and Hermione discover their feelings for each other later in life, after all their adventures. They get married and decide to start a family. Their baby could inherit some of their magical talents, like Harry's ability to speak Parseltongue and Hermione's exceptional academic skills in magic. The story could then focus on how they raise the child in a world that is still recovering from the dark times of Voldemort.
In fanfiction, it's often about bending the rules of the original universe. It could be possible through magical means that weren't explored in the original books. Maybe a powerful spell went wrong and created an unexpected bond between Hermione and Severus, leading to the birth of a baby. Another idea could be that in an alternate reality, their relationship developed in a completely different way, allowing for such a situation to occur.
Another possibility is that they give the baby a name with a special meaning in the wizarding world. Maybe a name related to an ancient magic spell or a magical creature. For instance, for a boy, they could choose 'Phoenix' which represents rebirth and strength, just like the phoenix in the wizarding world. For a girl, 'Aria' which could be associated with a magical melody that has the power to soothe or protect.
Some of the more traditional pure - blood families might oppose it. They have strict ideas about family and bloodlines, and Harry and Hermione's situation doesn't fit into their narrow view. For example, the Malfoys might initially be against it, seeing it as a break from the 'normal' wizarding family structure.
Well, their friends' reactions would be a mix of surprise and joy. Some, like George, might make jokes about how Harry and Hermione finally got together. But deep down, he would be happy for them. The other Hogwarts professors, like McGonagall, would be proud to see two of their best students starting a family. She might even offer to babysit on occasion. The friends would also come together to throw a big celebration for the baby's birth, and it would be a time for the wizarding community to celebrate the new addition and look forward to a bright future with this new generation.
Their relationship would become more intense and committed. Having a baby together means they are now a family unit. They would have to rely on each other more than ever. There would be a deeper level of trust and understanding between them. They would also have to communicate better to make decisions about the baby's upbringing.
Obviously, Ron and Hermione are the main characters as the baby's parents. Their personalities play a big role. Ron's humor and Hermione's intelligence are often passed on to the baby in different ways in the stories. Also, Harry Potter sometimes makes an appearance as the baby's godfather or just as a close family friend.
There might be a fanfiction where Ron and Hermione's baby gets into some sort of adventure in Hogwarts even at a very young age. For example, the baby might end up in the Forbidden Forest by mistake and befriend a magical creature there. This would add an element of danger and discovery to the story.