On the special, Hye Soo (IU) and Wang Eun (Baekhyun) was shown having an argument, going as far as grabbing each other's hair. Hye Soo says, "You're hitting a girl," while Wang Eun responds, "You're a woman? You're a bag of rice."
This gives more insight into the two characters dynamic in the series, letting viewers know that they definitely do not get along.
'Scarlet Heart: Ryeo' premieres on August 29 KST!