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.
Perhaps a fanfiction where Baby Steven gets lost and Rub and Sapphire go on a quest to find him. Along the way, they encounter various challenges and have to use their combined powers and their love for Steven to overcome them. It could show the deep bond between them and how much they care for the little Steven.
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.
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.
In the fanfiction, Ruby and Sapphire could be having trouble adjusting to life in a new town. Steven, who has experience with change, could introduce them to new friends and show them all the fun things about the place. Meanwhile, they could teach Steven more about their unique Gem culture, like how they fuse and their special powers. This would create a story full of cultural exchange and friendship building.
One plot idea could be that Sapphire and Ruby are having a disagreement about how to best protect Steven. Sapphire, with her future vision, sees a potential threat approaching in a very different way than Ruby does. This leads to some tension between them as they try to figure out the best course of action for Steven's safety.
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.
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.
The relationship can be developed through shared adventures. For example, they could go on a quest to find a rare gemstone that has special significance for all of them. During this journey, they would have to rely on each other's strengths, which would deepen their bond.