News outlet OSEN recently put together a list of reasons why K-drama characters tend to betray their friends.
There are many instances in K-dramas where characters must betray their friends in order to save their family members from trouble. Sometimes their parents will be sick, or their children will be held captive. As the saying goes, blood is thicker than water.
This is when human desires come into play. Its sometimes human nature to want more money and power, but this can turn into a reason for betrayal. In the hit drama Defendant, for example, the character Kang Joon Hyuk (played by Oh Chang Suk) betrayed his friend Park Jung Woo (played by Ji Sung) to attain some power.