Physician Kwon is initially introduced in Under the Queen’s Umbrella as a physician to the late crown prince but his most recent reveal shifts the landscape of the series significantly.
When the former crown prince first reveals his sickness to the Queen, she tries to keep it a secret from the rest of the palace and Physician Kwon is the man responsible for treating him. However, as time progresses, it appears that Physician Kwon has a lot more layers to him than others could have imagined.
Angel of death
Physician Kwon was just doing his duty by taking care of the crown prince but he was forced to do it in secret due to the sensitivity of the issue. He does his best but the crown prince’s health does not improve.
After Seongnam gets a prescription from Master Toji, Physician Kwon is hesitant to follow it because it is not recognised by the royal clinic. The Queen later insists that he do it because they are desperate for the crown prince to get better.
The crown prince eventually gets better but soon after dies after coughing up blood. There is no evidence of poisoning and an investigation reveals that medicine from outside the palace was used.
The state councillor who is against the queen uses this information to bring her down but she manipulates the situation to save the crown princess and her child.
In reality, the crown prince was poisoned by Physician Kwon himself on the orders of consort Hwang, with whom he was quite attached. The physician is banished from the palace without the truth being revealed.
Soon after he is banished, the first person Physician Kwon meets is Master Toji, who turns out to be his mentor. Later, it is revealed that they are both involved in a rebel group that plans to overthrow the King because they support the former regime.
They get rid of Seo Ham-deok after he is captured and even convince Prince Uiseong that there is some merit to their cause. The Queen and Seongnam find some evidence that proves Physician Kwon did have something to do with the late crown prince’s death.
They summon him back to the palace and gradually learn that Master Toji is actually Yoo Sang-uk, the former Royal Physician who treated Crown Prince Taein when he was suffering from Hyeolheogwol.
Physician Kwon aims to use his proximity to the Queen to find the records they’re searching for that will prove that Taein didn’t die of natural causes and was actually murdered.
Finally, it is revealed that Physician Kwon is actually the son of the deposed Queen Yoon and the younger brother of Taein, explaining his involvement in the rebellion and giving him a rightful claim to the throne.