Lydia

[ENG SUB] Deleted lines from the script, Li Lun and Zhao Yuanzhou/Zhu Yan, EP04 & EP33

Even though the whole thing is a plot to mislead the Dragon Princess, ZYC means every single word he utters. He's being completely vulnerable and open; his feelings and sentiments are real and, in the end, WX and ZYZ get carried away by his heartfelt sincerity. He makes the lie real. Because, let's face it, eventually it will come down to it and ZYZ will do something like half-killing himself to help ZYZ, especially since it really looks like he wants to use the scale to save WX who might have really been poisoned.

The sword is his family heirloom, the one thing he truly connects with his older brother, and everyone wants that sword, but he would throw it away without any hesitation, if repairing it meant hurting ZYZ or him dying. Honestly, it almost looks like he is totally fine with it, getting rid of the possibility of him having to kill him with it one day.

He is so adamant about and steadfast in that he won't allow ZYZ to sacrifice himself for him, and in a way, he is actually picking him over BJ, or rather he could give up on BJ rather than save him at all costs.

Translation: "You are more precious to me than anything in the entire world." FETCH MY SMELLING SALTS!

ZYC's words shake ZYZ to his core, it floors him that someone would choose him, the most evil great demon, above everything, that he would even choose him over the adorable BJ.

Demon Daddy thought he would show an Oscar-worthy performance, but he ends up going through the most intense therapy session of his life. All these words are everything he needed to hear in those past 8 years so much, but didn't know it.

Everyone wants not only to be part of a family, but to be someone's special person, someone's main person, someone's irreplaceable person.

And this theme - in subtle but completely intentional hints - is seen in the ZYC/ZYZ/LL relationship.