oh gosh okay so this might not make too much sense and i might ramble but walk with me!!
initially it started off as a very simple idea for a mystic messenger au, where zen (one of the characters who had red eyes and white hair) was a vampire who worked the night shift in a cafe. it was just a random silly thing floating around in my head that never really went anywhere until around december of last year when i really got into txt and the idea resurfaced. I wanted to write a coffee shop au, but for the longest time i've only ever written fantasy stories (and plus this would be my "re-debut" into the world of writing fanfic) and so i was thinking of how i can insert low fantasy elements into a coffee shop au...to be honest most of the ideas kind of were spontaneous since I decided to mostly pants this story instead of planning anything out like i usually do. So I can't say for sure what my prime source of inspiration was, rather it was more of a culmination of different little things that happen to come together every time i sit and type. I have a vague idea in my head of course, but it's really a toss up of what happens when i have my keyboard out haha.

anyways, sorry for the terribly long answer but I appreciate this question so much my love!!