Notes on the BL fanfiction series "Love Debt" for "The Mystic Nine": It's mostly an all-Zhang Qishan setup, split into three main storylines: 1 is Zhang Qishan and Er Yuehong, 2 is Zhang Qishan and Chen Pi, and 3 is Zhang Qishan and Qi Tiezui. The third timeline is set quite a bit later than the first two, while the first and second run more or less in parallel. Later, when I wrote a sequel to the first storyline, it was basically incorporated into that story, making it 1-2. So although the three storylines are all part of one tale, they can also be read separately. They're all short stories, and the installments don't necessarily connect, so it's fine to read them individually.
"Dreams of the Past" was the first piece I wrote, so you can read it as a prequel or an extra. It was only after finishing it that I settled on the tone for "Love Debt."
Why don't you write it? I looked at both sides and it was discontinued.