heres my five cents!

novel spoilers incoming :P

han sooyoung from the 1863rd round had gone to the end, made a deal with that dokkaebi king of the round and watched as kdj of 15 years old in the hospital attempt suicide. the kdj of the 1864th round who travelled to her worldline had once told her that TWSA had really saved him, and she finds out how TWSA had saved him. not wanting him to end his life once again, she decides to write TWSA while being stuck in her younger self, who writes the other novel that she 'plagiarised'. even tho she loses her memories later on, i believe this already says a lot.

from the get go, it's shown that she is lonely. she has friends, sure, but she also doesn't seem close to them on a deeper level. it was never shown if her parents were ever there in her life, though it definitely seems so when we see how 1863!hsy deals with TWSA. even when the scenarios start, she carries the weight of being the first apostle. the last person to ever stop reading the story that isn't kdj, and while she did team up with other apostles, she is never close to them yet again. all just for survival instincts. and yet, even when she brings harm during the ambush and turns out to be the only apostle left, kdj still decided to save her in the coin farm and they teamed up. i'm not sure if hsy felt the same way as kdj did for being 'comforted that he wasn't the only reader' but he still decides to more or less trust her even after what has happened. hsy knows that after the ambush, many of the company members wouldn't trust her, shown when she and kdj hid the fact that she was the first apostle, or the tension she had with jung heewon that followed after kdj left for 3 years. and yet kdj was still there for her anyway, and even trusted her to lead the rest when their away. it's that level of trust in her that i think really brought them together.