One great young Amethyst fanfiction could be about her early days of training. It might explore how she learned to control her powers and interact with the other Gems. For example, a story could show her struggling with a new form of attack but finally mastering it with the help of Pearl.
In Steven Universe fanfiction, the relationship between Steven and Amethyst can be really interesting. They are both very different characters. Steven is kind - hearted and has a strong sense of justice, while Amethyst is more of a free - spirited and somewhat rebellious character. In some fanfictions, their relationship might develop into a deep friendship where they support each other through different challenges. For example, Steven could help Amethyst come to terms with her insecurities about being a 'lesser' gem compared to the others.
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.
First, study Amethyst's character. Notice her traits like her playfulness and her insecurities. Then, come up with a unique plot. For instance, you could set it during a time when the Gems are facing a new threat and Amethyst has to use her shape - shifting ability in a new way.
There might be such a fanfic. The 'Steven Universe' fandom is quite large and creative. However, it's also possible that it doesn't exist. You could try searching on popular fanfic websites like Archive of Our Own or FanFiction.net to see if there's a story with this concept.
A common theme is innocence. Since she's a baby amethyst, the fanfictions often explore her naivete and how she discovers the world around her. Another theme is growth. It shows how she develops her gem powers and her personality over time. Also, the relationship with the Crystal Gems is a big theme, like how they protect and guide her.
Another option is that it's a human who has somehow discovered the existence of Amethyst and the other Gems. This human could be a mad scientist type who wants to study Amethyst's unique gemstone and abilities. He or she might not understand the full implications of what they're doing and just see Amethyst as an interesting specimen to experiment on.
Well, in such a fanfiction, the other Crystal Gems might go on a frantic search for Amethyst. They could face many challenges along the way, like dealing with new enemies or having to make difficult choices to get her back.
One popular 'Steven Universe Baby Amethyst' fanfiction might be 'Amethyst's Early Days'. It delves into her experiences as a baby gem on Earth. Another could be 'Baby Amethyst and the Crystal Gems', which focuses on how the other Crystal Gems took care of her. There are also fanfictions that explore her relationship with Steven during her baby gem phase.
One possible theme could be discovery. As I said before, if the lemon is some sort of new or magical object, the characters are on a journey of discovery about it. Another theme could be acceptance. If 'lemon' is a new character or concept, the other characters have to learn to accept it. For example, Amethyst might be more open - minded while others like Garnet or Pearl might be more skeptical at first.