The difference between Solar and Yongsun is that only one of them loves her, Byul thinks. 

Sometimes, it's like Byul is seeing double. She was the one who had a twin concept but Yongsun was dual in nature more than any other person Byul had known. 

It's not that Yongsun took advantage of her. It's that Yongsun never seemed to let Byul catch her just being herself. She never knows which version she is going to get — the woman who pulls her closer or the woman who pushes her away. 

Unfortunately for her, whether it's Solar or Yongsun, Byul had only known to love the other woman regardless. Solar doesn't have to be with Moonbyul only or Yongsun doesn't have to be with Byul only. Any and all version of her loves any and all versions of Yongsun.

It's both a curse and a blessing. 

Sometimes, Byul wishes she can slice her heart in half, right down the middle. But she knows that doesn't quite solve the problem of knowing which version of the older woman it goes to. 

Sometimes, it feels like Yongsun has two of her. A Byul that loves Solar and a Byul that loves Yongsun. 

(The truth is, though, is that it's just one Byul. One Byul loves two, three, and even a million of Yongsun. But Yongsun doesn't seem to know that. Sometimes, it feels like she doesn't even know herself.)

Yongsun thinks Byulyi is smart for making use of Moon as her public moniker. 

The younger woman gets to choose which side of her to show other people — the light side or the dark side — and never necessarily the whole. She has the freedom to be shined on or to shine on others. She gets to both give and to receive. 

That's the difference between the both of them, Yongsun thinks. Byul could afford to give herself in parts but Yongsun has only ever known how to give herself in whole. Completely, irrevocably, and devastatingly so. 

It's hard, sometimes, to not feel disoriented when she's Solar. Even more so when she's Yongsun. The difference is as stark as day and night. 

She goes from being surrounded with lights, cheers, and applause to being by herself in the silence with only her doubts to keep her company. 

It's not fair, Yongsun knows, to take it as though she is the only one with that burden to bear. But that doesn't make it easier for her to handle it, either. 

Sometimes, when Byul loves her, Yongsun doesn't quite know if the younger woman actually does. The older woman knows very well that loving Solar doesn't have to mean loving Yongsun, and loving Yongsun doesn't have to mean loving Solar, either. 

Sometimes, though, Yongsun feels like she is neither of them. So it follows that Byul does not love her if she isn't any of them. 

That's the truth, isn't it? Byul doesn't have to love her. 

(So, Yongsun is terrified because she does. Yongsun knows Byul does.)

(But that isn't quite enough.)