One idea could be a story where Rub and Sapphire are taking care of Baby Steven and they are teaching him about the different Gem powers. For example, they could show him how Sapphire can see into the future and how Rub can use his strength in a positive way. This would be a really cute and family - friendly fanfiction.
The plot could be that an old enemy from Rub and Sapphire's past resurfaces when they have Baby Steven. This enemy might want to use Steven for some evil purpose. So, Rub and Sapphire have to protect Steven at all costs. They use their unique abilities and their love for each other and Steven to fight off the enemy.
The unique relationships. Ruby and Sapphire's love for each other and their new role as parents to Baby Steven create a lot of interesting story possibilities. Their different personalities also add depth. Ruby is more fiery and impulsive while Sapphire is calm and collected, and seeing how they interact with Baby Steven, who has his own charm, is fascinating.
Love is a very common theme. Their relationship is often explored in-depth, from the early days of their meeting to their deep, abiding love as Garnet. Another theme is loyalty. They are always there for each other, and this loyalty is highlighted in many fanfictions. For example, in stories where they face challenges together, their loyalty to each other never wavers.
You can try fanfiction websites like Archive of Our Own (AO3). There are a lot of talented writers who create stories about Ruby, Sapphire and Baby Steven. Just use the search function on the site and type in relevant keywords, and you'll be presented with a variety of fanfictions to choose from.
One popular Ruby x Sapphire fanfiction is 'A Tale of Two Gems'. It beautifully explores their relationship with lots of sweet and tender moments. Another great one could be 'Ruby and Sapphire: Bonded Hearts' which delves deeper into how they support each other in different situations. And there's also 'The Ruby - Sapphire Union' that shows their journey together in a really creative way.
Baby Steven was in the garden. He saw a beautiful flower that was as big as he was. His eyes widened with wonder. He tried to touch it but his little hands couldn't quite reach. Pearl noticed and gently lifted him up so he could feel the soft petals. Steven babbled happily, his baby talk sounding like a sweet song. The other Gems gathered around, smiling at the adorable scene.
In the context of the show, since Sapphire is in a relationship with Ruby, if we consider the concept of a 'father' in a non - traditional sense, Ruby could be seen as the co - parent. Gems don't reproduce in the same way as humans, but their relationship could be the equivalent of a parental unit in this fanfiction.
In a 'Steven Universe Sapphire Pregnant' fanfiction, perhaps the pregnancy is unexpected. Sapphire could start having premonitions about the future of their unborn child. The story might focus on how the other characters in the show react to the news. Some might be overjoyed, like Pearl who loves new life among the Gems, while others could be more cautious, thinking about the potential dangers in their world.
To develop their relationship, you could explore their past. Maybe there were times when they first fused into Garnet and had doubts about each other. By delving into these memories and how they overcame them, it can strengthen their relationship in the fanfic. Also, having them face new challenges together, like dealing with a new type of gem enemy, and seeing how they support each other through it.