Love and adventure are often present. Characters might go on quests to find the diamond or face challenges to protect it.
Emotional exploration is quite common. Since they are complex characters, fics might look at their hidden emotions, like love, envy, or respect. For example, a fic could show how they struggle to understand their feelings for each other. Friendship or a deeper relationship is also a theme that comes up a lot in these fics.
In 'pink diamond x yellow diamond fanfic', a common theme is the concept of change. How they change over time, either due to external factors or because of their relationship with each other. For example, yellow diamond might become more empathetic because of pink diamond, or vice versa. Another theme is the idea of legacy. Since they are diamonds, their actions and relationships can have a significant impact on their legacy, and this is often explored in fanfics.
One common theme is the clash of cultures between the diamond dogs and the ponies. Since they have very different ways of life, it often leads to interesting situations in the fanfics.
One common theme is self - discovery. The OCs often start out not fully knowing their potential in the baseball world of Diamond no Ace, and as the story progresses, they discover their strengths and weaknesses. For example, an OC might realize she has a great batting eye but needs to work on her speed.
One common theme is friendship. Despite their differences, fanfics often explore how they could become friends. Another theme is growth. Both characters can grow and change in the stories.
A fanfic often takes elements from an existing work. So perhaps this 'a diamond in the sky fanfic' is based on a science - fiction or fantasy universe where there are unique elements in the sky. The diamond might be a symbol of power, or it could be a source of mystery that drives the story forward. For example, characters might be on a quest to obtain the diamond for various reasons, such as saving their world or unlocking a great secret.
One common theme is power dynamics. Since Yellow Diamond is a very powerful figure and Peridot is much lower in the hierarchy, their interactions often explore this difference in power. Another theme is redemption. Sometimes, the fanfics will have Yellow Diamond seeking redemption for her past actions, and Peridot plays a role in that process.
The concept of a diamond in the sky is very alluring. It creates an image of something precious and unattainable in a vast and mysterious place.
A common theme is transformation. The sky changing colors can symbolize a character's inner change. For instance, a character who was once shy and dull might be associated with a gray sky, but as they grow and become more confident, the sky in the fic might turn into a brilliant blue or a warm orange.
Love is a very common theme. The relationship between Bloom and Sky is often explored in depth, from the initial attraction to deeper emotional connections.