One popular theme could be exploring different relationships. For example, how a female Steven would interact with the existing characters like Pearl, Amethyst, and Garnet. Maybe she'd have a different dynamic with them, bringing out new sides of their personalities. Another theme might be self - discovery. Since Steven in the original series has a journey of understanding himself and his powers, a female Steven could have a similar yet distinct journey, perhaps facing different challenges due to being female in the Crystal Gem world. Also, themes of friendship and loyalty are likely to be explored, as they are central to the 'Steven Universe' series.
The theme of identity could be really prominent. A female Steven might struggle with the expectations placed on her by the Gems, who are used to the male Steven. She could question whether she can truly fill his shoes or if she should create her own identity within the group. Additionally, power usage and control could be a theme. How would a female Steven handle the powers she inherits? Would she use them in the same way as the male Steven or develop new techniques? And of course, the theme of family would still be there. She'd have to deal with her connection to Greg and how that changes or stays the same.
One possible theme is growth. Both Peridot and Steven grow throughout the original series, and the fanfic could continue that growth in their relationship. They might learn to understand each other better and become stronger individuals as a result.
A really interesting plot twist in these fanfics can be when Spinel gets corrupted again, but this time Steven has to find a completely different way to heal her. It challenges his usual methods and tests their relationship. Another plot twist could be that Spinel starts to have dreams or visions about Steven's future, and she has to decide whether to tell him or keep it a secret. This can lead to a lot of internal conflict for Spinel and also affect her relationship with Steven in unexpected ways.
One popular theme is redemption. Spinel has a troubled past, and many fanfictions focus on her journey towards redemption with Steven's help. For example, stories where Spinel tries to make up for her past actions.
The character design of female Steven may vary in many aspects. For starters, her overall physique would be more in line with a female body type, which could influence her movement. She might move more gracefully compared to male Steven. Her accessories could be different too. Instead of the simple star on his shirt, she could have a more elaborate necklace or bracelet. Her hair color could be the same, but the texture could be silkier. When it comes to her powers being represented visually, the effects could be more fluid and elegant, rather than the more straightforward visual effects associated with male Steven.
Well, one aspect could be the unique relationship between Peridot and Steven in the fanfic. Peridot is such an interesting character with her growth and development throughout the series, and when paired with Steven, there can be many new storylines. Maybe it focuses on their friendship deepening into something more, or perhaps it's about them going on adventures together that are different from the main plot of the show.
A common plotline involves Spinel struggling to fit in on Earth, and Steven being her guide. He shows her the beauty of Earth and its inhabitants. This can lead to a deepening of their relationship as Spinel starts to trust and rely on Steven more. Another plotline could be Spinel having nightmares about her past, and Steven being there to comfort her, which further cements their bond.
Friendship is also a big theme. Even though Steven is a baby, the fanfictions show the start of a beautiful friendship between him and Garnet. Garnet is patient with him and they have these sweet moments together that build the foundation of their relationship. In some stories, Garnet teaches baby Steven about the world around them, which is a great display of their friendship.
Adventure is also a common theme. They go on different quests or face various threats together. This could be something like exploring an ancient gem ruin on Earth or fighting off a new enemy. The theme of acceptance is important too. Accepting each other's flaws and differences. Amethyst accepting Steven's sometimes naive view of the world, and Steven accepting Amethyst's wilder side.
Peridot is quite popular too. Her unique personality, especially her growth from a somewhat antagonist to a more friendly character, makes for great storytelling in crossovers. In a crossover with 'Ben 10', Peridot's technological knowledge could be paired with Ben's Omnitrix - related adventures.
One popular crossover is having the Crystal Gems from Steven Universe team up with the Avengers to fight a common enemy. For example, they could battle a powerful alien threat that neither group could handle alone. The unique powers of the Crystal Gems, like Garnet's future vision and Steven's healing powers, combined with the Avengers' superhuman abilities would make for an exciting story.