I haven't actually read this specific fanfiction, but generally, in fanfiction involving Lucoa and Shouta from 'Dragon Maid', it might explore their unique relationship. It could be about how Lucoa, with her dragon nature, interacts with Shouta in different scenarios. Maybe it shows her protecting him or them having adventures together.
One common theme is the contrast between their species. Lucoa being a dragon and Shouta a human creates an interesting dynamic. Another theme could be growth, as they learn from each other.
I've read a 'dragon maid lucoa fanfiction' that focuses on Lucoa's past. It delves deep into her history as a dragon in her original world. It describes how she came to be the way she is in the present day, with her unique personality traits. There are flashbacks of her interactions with other dragons and how she learned about the human world over time. This fanfiction really adds more depth to her character.
The setting of the 'Maid Dragon' universe also adds to the allure. It combines the magical world of dragons with the ordinary human world. Fanfics can explore different aspects of this combination, like how Lucoa adapts to human customs or how humans react to her dragon - like powers. For example, a fanfic might show Lucoa trying to cook using her dragon fire in a human kitchen, which can lead to hilarious situations.
There's also 'Lucoa and the Dragon Bond'. In this fanfic, it focuses on the special bond Lucoa forms with another character. It's filled with heartwarming moments and great character development. It shows how Lucoa's presence affects those around her in unique ways.
Another possible fanfiction could be about Lucoa's past. How she was in the dragon world before coming to the human world. It could explore her relationships with other dragons there, and what led her to decide to come and live among humans. This would give readers a deeper understanding of her character.
I'm not sure which are the most popular ones specifically, but some might focus on Lucoa's interactions with Kobayashi. For example, a fanfiction where Kobayashi asks Lucoa for advice on dealing with the other dragons.
One common theme is friendship evolving into something more. Often, the two female characters start as friends or comrades in the dragon maid world and then their relationship deepens romantically.