Well, 'Beyond the Border Walls' is a really cool fanfic. It focuses on a group of characters who are trying to break through some hidden barriers in the Border world. It has some great action scenes and character development. Also, 'A Border's Secret Alliance' is quite good. It reveals some secret relationships between different factions in the Border manga's setting.
Well, 'A Dangerous Gaze' manga stands out because of its complex characters and unexpected plot twists. The detailed world-building also adds to its charm. The way it handles themes like mystery and suspense is quite different from other mangas.
I recommend "There Are Seven in the Tang Sect." The female protagonist of this novel is called Tang Qi. She is the pearl of the Tang Sect and is known as the seventh generation of the Tang Sect. However, due to her gender, she was abandoned by her father at the border. She disguised herself as a man to survive and was very unfavored. She had a brother who doted on her, but he was not in the Tang Sect. I hope you like this fairy's recommendation. Muah ~😗
First, study the original Border Manga carefully. Know the characters, the plot, and the world - building. Then, come up with an interesting concept that can fit into the existing universe. For example, you could focus on a minor character and give them a major role.