I've written a fic about this before, but a comment I got made me realise that the connection between Mobei-Jun isolating himself after his first time in the human realm and Xiang Fei isolating himself to write PIDW isn't something a lot of people pick up on.
I felt like it was something obvious. The way the novel went out of its way to mention they were both isolated because they wanted to survive in some way. Survival meant something different for them, Mobei-Jun knowing what it's like to fear for his life and Xiang Fei devoting himself to something that will help him survive, but it was survival all the same.
It always felt like this is what drew Mobei-Jun to Shang Qinghua to me. Their first meeting was Shang Qinghua begging for his life, and I am to believe this means nothing to someone who wished his doing the same meant something to those humans? No matter how pathetic it was, seeing someone value their life so much must have done something for him.
The theme of survival, and wanting a life felt like such a prominent theme in the Shang Qinghua chapter, from both of them. I doubt that was a coincidence. After all that talk of survival, of being happy with the bare minimum, didn't it feel like the chapter ended by choosing more than survival, choosing to live a life?
I truly believe that by choosing each other, they chose to do more than survive. There is a reason I started shipping Moshang after being uninterested by the way the fandom portrayed them, and that is because people aren't talking about the beauty that is their story in regards to life and survival and choosing to seek happiness when you learn you can do more than just the bare minimum.