The Crystal Gems would be in deep mourning. Garnet, being a fusion of love, would feel a profound sense of loss. Pearl, who has been so close to Steven, would probably retreat into herself, lost in memories. Amethyst might become angry and lash out at the world. Connie would be shattered, as Steven was not only her friend but also her partner in many adventures. The Diamonds would likely be shocked. Yellow Diamond might question her own actions and how they might have led to this. Blue Diamond would be consumed by grief, and White Diamond would perhaps see it as a sign that her ideas of control were wrong. Each character's reaction would be a complex mix of emotions, and it would reshape the relationships in the fanfic.
A time travel fanfiction could involve a character other than Steven, like Connie. She could travel back in time to meet Rose Quartz. This would be an interesting encounter as Connie could ask Rose about her past, her relationship with Greg, and her hopes for Steven. It could also create a situation where Connie has to make sure she doesn't accidentally change the past in a way that would harm the present.
In 'Steven Universe Watch the Future fanfiction', Steven is bound to be a central figure. He's the protagonist of the original series, after all. Alongside him, the Crystal Gems - Garnet, Amethyst, and Pearl - are very likely to be main characters. They've been with Steven through thick and thin. Additionally, characters like Peridot, Lapis Lazuli, and Bismuth, who have become important parts of Steven's life in the later parts of the series, could also be main characters. Connie, with her connection to Steven and her own growth in the story, is also a strong candidate for a main character.
If it was a crossover with "She - Ra and the Princesses of Power", Adora could be a main character. Her strong leadership and the power of She - Ra would be an interesting contrast to Steven's more laid - back leadership style. Together, they could fight against a common enemy that threatens both their worlds.
One idea could be a crossover with "Adventure Time". Finn and Jake could visit Beach City and interact with the Crystal Gems. They could go on a mission together to stop a new threat that combines the magic of both universes.
One common theme is self - discovery. When a character travels through time, they often learn more about themselves. For example, Steven might travel back to a time when he was younger and realize how much he has grown. Another theme is fixing past mistakes. Maybe a character goes back to prevent a certain event that had negative consequences in the future.
In the context of the show's universe, it's a bit of a strange concept. Since fanfiction exists in our real - world fandom and not in the show's world directly. But if we were to imagine a meta - situation where he could access it, I suppose it could be possible. However, it would be a very surreal situation for him.
He would probably have a very mixed reaction. On one hand, seeing how fans view his world and his story could be really cool. He might enjoy seeing different versions of himself and his friends. However, if there are inaccuracies or things that go against his values in the fanfiction, he could also be a bit put off. It really depends on the nature of the fanfiction he's reading.
A great fanfiction could be about Steven and Connie swapping bodies. This would lead to a lot of humorous moments as they try to figure out how to act like the other. Connie would struggle with Steven's powers, and Steven would have to deal with Connie's more studious and disciplined life. It could also be a chance for them to understand each other on a deeper level.