Descendants of the Sun shows absolutely no signs of slowing down. It is only in the second week and it is pulling in ratings of 24.1%. A mixture of the hype, the star power, the whopping budget, and the intensity of the plot and romance is the reason for its success. Writer Kim Eun-sook always likes to keep her viewers on their toes, and this drama proves to be no exception.
Kim Eun-sook is also known for characters who have drastic mood swings and changes in behavior. We really start to see that propensity fulfilled in this fourth episode. Si-jin vacillates between his jokester persona, his honorable soldier identity, and a strange mash of wounded male ego and lovelorn fool. His emotional swings and monologues are a bit heavy-handed for what has been established as his character, but it is Song Joong-ki who evens the mood swings out and makes him believable. I do believe, based on the huge quantities of articles published since the start of this show and my own two eyes, that this man is a major reason for the insanely high ratings. Not only is he handsome, but he embodies an intensity in his expressions and stance that are compelling. Even his English line delivery is convincing, which is very much appreciated since all the other non-native (and native) English speaking actors butcher their lines.