I headcanon (and maybe it is canon?) that Lee Soo Hyuk was the first person to actually explicitly tell Kim Rok Soo to live.
To try, to give his best.
It's not like KRS wasn't… living before. Technically it was surviving through adaptation and isolation but, yeah.
LSH guided him through a lot, said things no one had said before, and showed him how to live even without mentioning it once.
People talk a lot about KRS saving others, but I think the reason he does it that way is because he was saved that way first. You know, quietly, practically and without any demand for gratitude from LSH.
That's exactly what KRS repeats now each time.















