Hold on, the Dragon acknowledges Seddin as a non-exist being that exists, as in, if a higher power has changed the casuality of time to insert it there.
I have a theory, could Seddin be... the author of this universe book ? The self entitled God who has been seeing Rene/Kim Yi-Young over the years, and has finally got his chance to introduce himself in her life to gain her affection ? Or is him one of her old comrades from the tower in which his Soul has been reincarnated into this World as an act of pity by this God.
Like, this sadistic God way of making amends to get Rene/Kim Yi-Young to seek love and restoring her humanity before returning her to Earth.