As for the two princes who were switched, here is the other obvious literary foil.
The upright yet dashing Prince Myung Nong's foil is Prince Jin-Moo who is charming but devilish.
I will give five stars for KDSBH and 4 stars for empress ki Can't agree anymore! I have watched empress ki many times, it is the best of best, all the people in Korea and Asia love this drama, it was the best drama of 2013-2014 but king daughter is toooo long, I just watched it ones, there were a lot of borring scenes for filling the episodes, actors obviously can't do their best, king daughter can't compare with empress ki. incestuous affair and finding ways to justify it, the character is as bad as her sis.
It has great acting, great pacing, great writing, great chemistry between actors and great costumes.
Even though King's Daughter, Soo Baek Hyang did not have the most ravish sets nor a high budget-it was able to do more than most fancy sageuks have done in the past.
Great chemistry between Seol-Nan and Myung Nong was another bonus to this drama.
They had one of the best romances in Korean dramas.