One common theme is the anticipation and excitement of becoming parents. This can include scenes of them preparing a nursery or choosing baby names.
Another theme is how their relationship evolves during the pregnancy. Since they have a complex relationship in the original story, the pregnancy can add new layers of love, protectiveness, and sometimes even conflict as they navigate this new phase together. For example, Meliodas might be overly protective, which could lead to some minor disagreements with Elizabeth who still wants to be independent. And this all plays out within the magical and adventurous world they live in.
One common theme is their undying love for each other. Despite all the obstacles they face in the original story, fanfictions often explore how deep their love is and how they overcome new challenges.
Love and sacrifice are also very common themes. Since their relationship is a central part of the Seven Deadly Sins story, fanfictions often explore how far they are willing to go for each other. This could involve Meliodas sacrificing his power or Elizabeth putting herself in danger to protect Meliodas, and how their love endures through these difficult situations.
Love and sacrifice are very common. Their relationship often involves one or both of them making sacrifices for the other. For example, Meliodas might sacrifice his power to save Elizabeth.
Love is a very common theme. Their love story is often explored in different ways, like how they overcome obstacles to be together. Another theme is sacrifice, as both characters in the original work are known for their willingness to sacrifice for each other.
There are various fanfiction platforms where you can find such stories. For example, Archive of Our Own (AO3) is a great place to start. Just search for 'Elizabeth and Meliodas pregnant' on the site, and it will show you a list of relevant fanfictions.
One popular theme is the 'forbidden love' aspect. Since their relationship has many obstacles in the original story, fanfictions often explore how they overcome these. Another theme is 'alternate universes'. Writers like to create different settings where Meliodas and Elizabeth can be together in different ways, like in a modern - day AU or a fantasy AU different from the original.
One great fanfiction in this theme might be 'The New Beginning' where it beautifully depicts their journey into impending parenthood. It shows how Meliodas is both excited and a bit nervous, and Elizabeth is full of anticipation.
There could be some stress on their relationship too. The responsibilities of impending parenthood might cause some arguments. For instance, they might disagree on where to raise the child or how to handle the child's potential powers. But these conflicts would ultimately strengthen their bond as they work through them together, learning more about each other in the process.
The reactions of their friends and allies. In some fanfictions, Diane might be overly excited and offer to help with baby - sitting in the future. King could be a bit more reserved but still supportive. These interactions add depth to the story.
One plot idea could be that they face challenges from outside forces who are either jealous or see their unborn child as a threat. Maybe an old enemy tries to target Elizabeth during her pregnancy, and Meliodas has to go to great lengths to protect her and their future family.