Option 1: It is the 2FL's real name: 나비 (NaBi)
The sequence was this:
(Paraphrased)
- ML: "What's your real name?"
- FL: "Your reaction when I tried to touch you speaks that you still hate me. No, I won't give my real name."
- FL: *she leaves and a butterfly landed on her*
It was a hint to him that her name is 나비 (NaBi).
Why didn't she just tell him? Because names have powers. This is very common belief in many cultures around the world since the ancient times and to this very day. Even the penname/stagename one chooses has powers.
But, if you don't give your name (ie vocalizing it or handing out your ID), there is almost no power to it.
Since he still hates her, he might accidentally or intentionally curse her.
Now, even if the ML figured out the butterfly clue, it won't have any power. And his doubt if he guessed right guarantees there's zero power (doubt = 0 power).
So, no harm done.
Option 2: 2FL is now free of her burden
Someone asked about the connection between the 2FL's butterfly and the bonus scene butterfly, and this gave me an idea.
The butterfly landing on the 2FL's shoulder is a symbolic meaning that her child's coffin she's carrying on her back has been lifted. The 2FL is now free of her past, burden, and bitterness that controlled her life.
To explain that scene, they added the bonus scene.
In the bonus scene, we saw she FL hand a butterfly to the spirit possessing a man, then the spirit left.
In many cultures around the world, a butterfly is a bridge or channel to help souls move on to their next destination.
The evil spirit was refusing to leave but after he was handed a butterfly, it finally decided to move on.
Which explains the butterfly scene for the 2FL. What did the butterfly help to move on? None other than the child in the coffin on the 2FL's back. Her child she wouldn't let go.
She finally let go of her past, so a butterfly picked the child to help it move on.
