One interesting story could be about Pink Diamond's early days before she became a part of the Crystal Gems. It might explore her relationships with other Diamonds and how she started to question the Homeworld's ways.
Well, the formation of pink diamond in Steven Universe fanfic can vary greatly. Sometimes it's linked to ancient magical rituals or the convergence of powerful forces. It all depends on the creativity of the author.
Pearl, who was once Pink Diamond's servant, is another main character in many of these fanfics. Her loyalty to Pink Diamond, and how that loyalty has changed over time and affected her own character development, is a major aspect in these stories.
In steven universe baby pink diamond fanfiction, a great concept is the idea of baby Pink Diamond's dreams and aspirations. Since she grew up to be such a complex character, fanfictions could explore what she hoped for as a baby. Did she dream of ruling over planets? Or was there a part of her that always desired something different? Maybe she was curious about the stars and the unknown from a very young age, which later translated into her interest in Earth. Also, her early interactions with the gem technology around her could be an interesting aspect. How did she learn to use her gem powers? What was her reaction to the grandeur of Homeworld's architecture and machinery? All these elements can make for very engaging fanfiction stories.
One interesting aspect could be the exploration of new powers or abilities related to the Black Diamond. It might introduce unique storylines that deviate from the original series, like how the Black Diamond's presence affects the relationships between the main characters in the Steven Universe world.
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.
I'm sorry, I can't directly recommend specific fanfictions as there are so many out there. But you can start by looking on fanfiction.net or Archive of Our Own. Just search for 'Steven Universe baby Pink Diamond' and you'll likely find a bunch of interesting reads.
One interesting idea could be the cultural exchange between Pink Diamond and Steven. Since they come from different backgrounds within the Gem world, their meeting might lead to a sharing of unique abilities and knowledge.
One interesting male diamond fanfiction could be one that explores the backstory of a male diamond character. Maybe it delves into his past relationships with other gems, his role in the diamond hierarchy, and how he came to be the way he is. For example, a story could focus on his struggles with the strict rules of the diamond society.
One idea could be that Steven discovers a hidden memory of Pink Diamond that changes his perception of her. Maybe it reveals a side of her that was never known before, and he has to come to terms with this new understanding while also dealing with the reactions of the other Crystal Gems.
Obviously, Steven and Pink Diamond are the main characters. Steven, with his unique ability to understand and empathize with all beings, and Pink Diamond, with her complex and mysterious past. Their interaction would be the core of the fanfiction.