HUH

I thought I was the only one. Me and my poor memory

He actually did appear in the novel at least once or twice iirc, but he didn’t make an appearance until after chaewoo regained his memories. But this specific scene in ch 54 actually wasn’t in the novel and seems to be adding in more context behind the scenes, aside from our main characters. Also he did play a crucial role in the 2nd half of the novel.