Dennis might develop into a more responsible and patient character. Having a baby could force him to grow up in many ways. He could become more protective of his family.
Another aspect could be the future that Dennis and Winnie envision for their baby. They might have big dreams for their child, like going to a great school or having a particular career. And as the baby grows, there could be cute moments of first words, first steps, and all the milestones that come with raising a child in a fanfiction world.
One possible theme could be friendship. Even as babies, Dennis and Winnie could start to form a bond that will last as they grow. Another theme might be discovery. As babies, they are constantly exploring the world around them, and this could be a central part of the story.
Well, without actually reading the specific 'Dennis and Winnie baby fanfiction', it's hard to say much. But generally in a baby fanfiction, it could be about their early days as babies. Maybe it shows their first encounters, how they interact with their families, or the start of a special friendship even at that young age.
In a fanfiction of Dennis and Winnie, perhaps they decide to explore the outside world. Winnie, being a vampire, has to protect Dennis from the sun. They meet some friendly humans who are surprisingly accepting of them. Dennis starts to realize that he can be a bridge between the human and vampire worlds. They have a lot of fun, like trying human food for the first time and sharing vampire stories with their new friends.
Another reason could be that fanfiction can be a form of escapism. In the real world, there are often stressors and mundanities. But through fanfiction, Dennis and Winnie can immerse themselves in exciting, romantic, or mysterious stories. They can follow the adventures of their favorite characters or even discover new ones. It's like having a portal to a whole new universe where they can forget about their daily troubles for a while.
Love and family are very common themes. Their married life often focuses on how they build a family together and the love that grows between them over time.
There might also be secondary characters in the fanfiction. For example, their best friends who could play important roles in the story, like helping with baby preparations or providing emotional support.