Thanks, @GB. Your comment here,

As an aside: it occurred to me that young SE was brought up by a fisherman, and probably smelled of fish, but was forcibly transplanted to sweet smelling environments, while the real SE as Psycho smelled strongly of fish that he handles and is jealous of how nice fake SE smells.

reminded me that I have to comment on the many fish connections in the drama.

1. The youngter SE’s refusal to eat sashimi

I get it now. It isn’t because he disliked or was allergic to fish. It’s probably because he was homesick for his simple life back in the lakehouse. He was missing his foster father and his carefree days. And in his new environment, he felt like a fish out of water.

Noteworthy: the seafood plate was the first sign of his tender solicitude for HJ.

2. In Ep 9, after his foster father yelled at him for calling him “aboji,” he dropped his tin pail full of his fish he just caught. The camera then focused on the fish, gasping for air, dying on the ground. I see this as a foreshadowing. One, the Chairman’s son would be drowned and killed that evening. And two, SE would soon be taken out of his element and placed in the suffocating Paik household.

3. Also in Ep 9, Presidential candidate Paik received a box of assorted, mutilated and bloody fish. That was Psycho 406’s idea of a joke. He wanted to disrupt his parents’ taped interview by sending them a message (or a warning??) that he – their unwanted psycho son – was still very much alive. Instantly, Mrs. Paik had an inkling who sent it so she rushed off to see if he was still around.

This moment drove home to me that a mother’s love is truly unconditional. Despite everything she knew about her son, she still went after him.

4. In Episode 6, Hong InNa and HJ arranged to meet at the aquarium. Hong InNa was already there watching the fish. She chose the spot because she remembered that they often visited the place when they were kids. She found peace in the silent venue and HJ liked to watch the mermaid show.

To me, the fish in the aquarium symbolized their idyllic childhood. They grew up in an artificial place where all their daily needs were met and indulged. They weren’t raised in the wilds and forced to endure the elements.

5. In Ep 3, Psycho 406 was filmed gutting a fish with gusto. I already wrote about this. I said it was in keeping with his personality. The screenwriter wanted to project this image of the killer. He was wild, untamed, and brutal. He relished getting his hands bloodied. He wasn’t squeamish about killing and death. He would kill out in the open. He was unlike DoJae who preferred to do his killing furtively: he pushed HJ when no one was looking.

I could imagine him ripping SE apart with his bare hands.

6. The smell of fish

As you wrote, @GB, this is a reminder to Psycho 406 of what he lost, and SE gained since they were switched. Psycho 406 lost the luxury and privileges of being a Paik.

7. Fish eyes

In Korean Buddhist culture, however, the fish is a symbol of being watchful and vigilant. That’s because their eyes never close and are always open.

HJ and SE believed they successfully kept their marriage under wraps. In Ep 2, during his conversation with the British ambassador, he revealed his reason for never showing up in public with his wife. He truly believed that he had managed to hide his one and only weakness out of sight, and thus, out of danger. But as it turned out, there were eyes around him, and his enemies were targeting HJ.

8. Big fish in a small pond

This was SE in the beginning of the story. He was the big fish in a small pond. Everyone admired and trusted him. All deferred to him because he was the best there was. But it was all a façade. He was simply trying to go with the flow and to swim with the sharks to the best of his abilities.
And he derived this confidence from HJ’s presence behind him. He had to be strong in order to protect her.

9. The name of the webtoon writer is “dryeomulnyeo.”

Mind you, this is all a coincidence. According to the interview the webtoon writer gave recently, she chose the pen name “dryeomulnyeo”  because at that time, it was in vogue. Its translation is “dried fish woman.” (I think “eomul” means fishcakes??) The word refers to a person who appears to be fine outside, but when she comes home, she’ll roll around like a discarded object. Or like jetsam and flotsam.

I guess, this describes HeeJoo’s character, too, especially in the beginning of the story. In appearance, she seemed calm and collected. But inwardly, she was raging and plotting to divorce SE.

That’s it for now.