Haha, I think I get what you're asking. Without spoiling too much...
As things currently stand, MC knows a little shade magic. Very little. He is still out of balance. At our currently released point in the story, MC is the carrier of the white flame. The white flame is where fade magic comes from. With that logic, shade magic must come from somewhere, yes? That is explored in this next episode that I'm nearly finished with. Plus, we'll learn just where it all began. Fade (the character) and Shade are 'products' of their related magic. Goddesses (Fade Goddess, Shade Goddess). Fade magic is more focused on love, while shade magic is more focused on lust. But both are fed by sexual energy, and... something else I don't want to spoil yet.
MC (the 'King') rules over all of the dream world universe, fade and shade. Even though he is mostly out of balance (mostly fade magic) he has absorbed the white flame (when he saves his mom, then sees her again - and he gets hit with all the lightning and shit). From that point on, he became ruler of all of it. Even though he hasn't mastered shade magic, the Shade Goddess is still one of his subjects.
Anyway, yes I wasn't good with the plot on some of the earlier part of the story. But it sounds like you pretty much got the gist of it.