Chapter 1: Wow. Where to begin. This was incredible and beautiful and heartbreaking all at the same time!
My heart broke for Insoo when he was captured and killed, his desparate, yet resigned demeanor just so sad and he didn't deserve such a horrible death. And Seyong witnessing his death and becoming as distraught as he did was also heartbreaking. It's so sad when beings can't be accepted as they are. I am glad that Seyong took strength from what had happened to Insoo and carried it with him, helping him to endure the troubles and finally rise above it all. It was wonderful.
Also, I loved Hongki and Jaejin's relationship, and the way they were portrayed was great, with Hongki being a little TOO protective over him. Those two cracked me up, honestly.
The way you put Kyujong in was very smooth and I lived his character. He seemed to be a little darker somehow, and it was great.
I loved Seyong's character and how he grew in just a one shot. You put so much depth into his character and he was endearing, yet saddened me at the same time, with everything he had been through. I loved him.
The idea of the Celestials and the Chasm was very creative and the world you created in this story was great. Thank you for writing this for me. It was a wonderful story and one of the best one shots I have read all year. Merry Christmas, my dear♡.

This looks so interesting! I look forward to seeing what happens!