The Emperor smirking when Longhee exclaims that he should not question whether the Empress cuckolded him and had her bastard son be raised as a prince tells its own tale.
This chapter truly unveils what a complicated, sly and calculate character the Emperor is. For one, we know Longhee comes from a defeated country that has retained its nominal independence by sending Longhee to the palace. As such, her sons ascending to the throne would constitute a danger to the Empire, since it is assumed she may bias them favorably towards her own nation. However, the Emperor just had a chance to assess that Longhee did not try to grasp power. In fact, she seemed quite frightened, going as far as opposing the Emperor to his face in front of his chief advisor. This is a woman the Emperor can control. Unlike the Empress Consort.
The Empress Consort is a woman who has determined what her place should be from a very young age. She was but a little girl when she decided she would be Empress. Which implies that since her childhood she was sold the idea that this was not out of her reach. She must be coming from a powerful family. And a powerful family implies that they would be trying to grasp for power through the Second Imperial Prince Bongrim. And of course, as soon as Bongrim would have reached the age to rule, the Empress's family could have plotted to dispose of the Emperor and use Bongrim as a puppet so they could rule through him. But having three imperial princes implies that the great powers of the Empire would be pitted ones against the others. Each faction would have their favorite prince.
As Chief Advisor Jang said, Longhee has no backing. She is completely and totally dependent on the Emperor's favor. And here he is, pitting her against the Empress Consort, using her to keep the Empress Consort busy while he is plotting to displace the Empress's son of his birthright.
And oh, gosh, that slippery nonsense about Chief Advisor Jang being like family to the Emperor. This is a man who rejects his own flesh and blood, Bongrim, because he does not look the part of the Imperial Son. And here he is, talking about brotherly feelings to a complete stranger.
Now, the Empress Consort is an interesting woman. She is assessing the situation of the Emperor's favor, but does not seem to be fazed by it whatsoever. We remember that Bongrim said his mother, the Empress, was not allowed to give birth anymore. This is HUGELY important and needs to be remembered for upcoming chapters. And it makes sense. A woman who would give birth to a child with special needs or a child whose appearance was not considered as auspicious would be more than rejected in Ancient China. She could be killed. It is a testament to the Empress Consort's power that not only was she not deposed but her son is a contender for the throne. This is not a weak, unprotected woman. This is a dragon among harem women. Thus it is not surprising that she considers everything with a cold, frightening magnanimity. I am more scared of the Empress Consort's kindness than I would be of her rage.
Finally, Bongrim. My heart bleeds for that poor child. Think about it. Rejected by his father, born with deformity, not being disciplined when he needs it, not being praised when he deserves it. In Chapter 1, he showed a vulnerable side by expressing how much he wanted Sogeo to live so he could have a brother. And we saw how unhappy Longhee was at the idea of the Bongrim considering Sogeo his brother. Children of a same mother were supposed to ally with one another. Generally to face the children of another mother. It is so sad to think that Bongrim might be the loneliest character in this story. A father who rejects him. A powerful mother who works hard to keep that power. Servants who fear him, whether because of his mother or his appearance. And his appearance that he MUST KNOW to be different (children are not stupid, they realize when people do not like them or treat them with disdain - plus, children are very good at comparing). These circumstances are bound to shape Bongrim in the future.