When writing an imprint stories fanfiction, it's important to create a believable world. Whether it's a world based on an existing fandom or an original one, the rules of the imprint should make sense within that world. You should also develop the relationship that results from the imprint gradually. Don't rush it. Let the readers see how the characters change and grow because of the imprint. For example, if a character imprints on someone from a different social class, show how they navigate the differences in their upbringing and expectations. This will make the story more immersive and the imprint more meaningful.
A good imprint stories fanfiction needs a solid plot. You can't just rely on the imprint itself. For example, if it's an imprint between two people, create external conflicts like family opposition or a common enemy. Also, describe the emotions that come with the imprint in detail. Is it love at first sight? Or a sense of duty? By exploring these aspects, you can make your fanfiction more engaging.