These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Woo Ri and Young Gyu trying to get to Mi Sook in the fire, calling out to her even though she can't hear, and her finally turning to them as the gate closes down in between them.
Woo Ri telling Joon Ha what she would have told Ma Ru. And subsequently, him saying sorry (although he covers it up by telling her that's what he thinks her stepbrother would have said).
Young Gyu telling Woo Ri that Dong Joo isn't his son — he knows because he memorized Ma Ru's face while he slept. It was the only time Ma Ru wouldn't get mad at him. This is particular poignant in that the real Ma Ru witnesses this exchange.
Young Gyu: His eyebrows are like this and his eyes are like this and his nose is like this...
Joon Ha encountering his grandmother and telling her that he doesn't want to come back home.