The plot could involve Blue Diamond initially being hostile towards Steven. However, as they interact more, she realizes that Steven has a unique perspective on the world and the relationship between gems and humans. It could lead to a journey where they both learn from each other about acceptance and change.
It could be that Steven is on a mission to seek help from Blue Diamond for some sort of crisis in Beach City. Along the way, they have to overcome their differences. Blue Diamond may be reluctant at first, but Steven's charm and determination slowly break down her barriers, and they end up working together to solve the problem.
Maybe Steven tries to understand Blue Diamond's past and they form an unexpected friendship. For example, Steven might show Blue Diamond how the modern world has changed and how the gems are living differently now.
Well, perhaps in the fanfiction, Steven meets White Diamond when he's on a quest to understand more about the Diamonds' past. White Diamond is initially cold to him, but Steven's kind heart and unique perspective start to break through her icy exterior. They could end up having a deep conversation about forgiveness and change, which might lead to a new alliance or at least a better understanding between them.
One possible plot could be that Steven, having heard so much about Pink Diamond, finally has a chance encounter with her in a dream-like realm. They start to talk about the past, how Pink Diamond used to view the Earth and her complex relationship with the other Diamonds. Steven tries to understand her better and in the process, Pink Diamond gets to see how much the Earth has changed and how her actions still have an impact today.
Both characters could develop a mutual respect for each other. Steven would respect Blue Diamond's long history and power, while Blue Diamond would come to respect Steven's unique position as a bridge between two worlds. This newfound respect could change how they interact with their respective groups as well.
Perhaps Steven and Yellow Diamond end up having a long - awaited conversation. They could discuss the past, the reasons for the war between the Gems, and Steven could share his unique experiences as a half - human, half - Gem. This might cause Yellow Diamond to question her long - held beliefs and start to consider a different path for the Gem Homeworld.
Power and responsibility is also a theme. Given that Steven has unique powers and Blue Diamond has her own vast power and influence. Fanfictions often explore how they use or should use their powers and the responsibilities that come with them. In some stories, they work together to solve problems that require both of their powers and the right mindset to take on the associated responsibilities.
It could be another gem who doesn't want Steven and White Diamond to form an alliance. Maybe a rogue gem who fears that their combined power would disrupt the current power balance in the gem universe.
Perhaps the fanfiction could start with Steven having a strange dream about Pink Diamond. When he wakes up, he starts to notice small changes in himself, like his gem glowing pink more often or having strange new abilities. As he becomes more and more like Pink Diamond, he realizes that there is a connection between his mother and himself that he never fully understood. He then embarks on a journey to discover the truth about his transformation, along the way facing challenges from both the Homeworld and Earth - based gems who are either afraid of or intrigued by his new form.
One common plot element is the exploration of Blue Diamond's past through her interaction with Steven. Another could be a situation where they are forced to rely on each other in a difficult situation. For example, they might be stuck in an alien environment together.
One common theme is redemption. Blue Diamond has done some not - so - great things in the past, and in the fanfiction, her relationship with Steven often serves as a path to her redemption. For example, Steven's kindness and understanding can make her see the error of her ways.
The theme of discovery is also prevalent. Steven discovers more about the Diamonds through his encounter with Pink Diamond, and Pink Diamond might discover new things about Earth and the Crystal Gems. There's also the theme of family, as Steven's connection to the Diamonds is a sort of family - related one, and this meeting can further explore that aspect.