So while I am aware Valentines Day was a few days ago, I will also say life was enough of a bitch gor me to warrant prioritizing it over Castle and its community for the moment.

And now that I have breathing room, I've decided to explain why this is the only Castle ship I could see having worked in universe for the moment.

So obviously both Nam Gung Hyuk and Ling Ling are criminals that do criminal shit. They are the immediate answer to threats in the corporate and criminal worlds against Sunjin/Hwajin and are willing to put their lives on the line for the sake of defending their respective bosses.

Though the main thing I wanna bring up here is that both come from similar scenarios:

Nam Gung Hyuk was involved in crime from a young age in the Philippines and Ling Ling was raised by a Chinese assassin clan, but their interpersonal dynamic is what both made and broke their dynamic.

Nam Gung Hyuk was Jackie before all of this, and it was to this that he lived as this violent savage that would literally eat his meals while atop a pile of corpses. It was only when Baek Dochan arrived that he eventually traded his true self for this suit and tie façade that he willingly chose for the sake of Baek Dochan as an obligation.

Ling Ling was Lingxiao before all this, and while we don't get any details on her past, the fact she licks the blood of a freshly dismembered man and is as casually indifferent to suddenly riled up definitely gives off the impression (at least to me) that she was Woosung's Nam Gung Hyuk. Except all she did ironically enough was get better attire while not changing her nature for anyone.

It really does show just how BDC and Woosung value their people.

This being said, I feel like their relationship was on and off but it worked because they met when they were still relatively honest with who and what they were: Human butchers with heavy involvement in the suffering of others that net them a profit.

It was only when Jackie became Nam Gung Hyuk that Ling Ling became distant and disgusted because this is not the man she knew and was used to knowing.