Ruan Zhou was the quietest resident at the Heavenly Transit Station. He was a tiny guinea pig in animal form, and his personality matched: he never fought for anything, listened more than he spoke. Then he met Lu Ci.
In life, Lu Ci had been an interstellar commander. At the Transit Station, he could no longer hide his talkative nature. He'd grab anyone he could and tell them about the planets: the seas on Bluebell Star glowed, the candy trees were sickly sweet, and on Wind Star you had to hug a pillar to keep from being blown over. Ruan Zhou crouched beside the bench and listened without interrupting, carefully writing down every place name Lu Ci mentioned. Lu Ci once remarked offhandedly, "If we ever get out of here alive, I'll take you everywhere to see the sights."
Ruan Zhou took him at his word and remembered. Then he dragged Lu Ci along with him as they both plunged through the Gate of Rebirth.
After being reborn, Ruan Zhou carried an ever-thickening notebook and visited every planet Lu Ci had told him about. He asked everyone he met, "Have you seen a cheerful, talkative man?" The answer was always the same: "No. But there's a stern-faced officer who comes by a lot."
That stern-faced officer was the person he was looking for. In public, Lu Ci was the most reclusive commander in the Northern Frontier. Only around the little guinea pig did his golden-retriever nature come out. He didn't know Ruan Zhou had been reborn too, much less that he was looking for him. Separated by a wall, a fireworks display, or a page in a message book, they kept missing each other again and again.
Ruan Zhou wasn't in a hurry. He had plenty of patience and plenty of time. He thought, I've been everywhere. You're all that's left.
But when he finally found Lu Ci, he realized this man had been suppressing his true nature for half his life. That joking promise gradually became concern, and that concern slowly turned into something else.
The universe is vast, and the notebook is thick. They promised to travel it together, and it doesn't count if even one of them is missing.
Those who fall through together are bound to meet again.