Hyun Bin and Ji Sung each play men with multiple personalities in the currently competing dramas "Hyde, Jekyll and I" and "Kill Me, Heal Me."

"Kill Me, Heal Me" is the ratings winner in the competition, but that would have been hard to predict. And what many viewers don't know is that Hyun Bin was also offered the lead role in "Kill Me, Heal Me." According to the Korean media outlet TV Report, producers were very eager to have him. But he turned that drama role down and chose instead to star in "Hyde, Jekyll and I."

In retrospect, that might not have been the better choice.

Before both dramas aired, it was assumed that the drama Hyun Bin chose would do better since it was his first drama after leaving his two-year-mandatory military service. And he had a loyal fan following based on his roles in "My Lovely Kim Sam Soon" and "Secret Garden."

Also, "Kill Me, Heal Me" was offered to several actors, including Lee Seung Gi, only to snag Ji Sung at the last moment. That made the role seem less desirable. The role of Cha Do Hyun, who splits into different personalities, was not an easy one to play and could have been a disaster in another actor's hands. But Ji Sung took the role and played everyone of his personalities-from the defiant Shin Se Gi to the petulant Yo Na-with wit and comic style.

In an interview with TV Report, Ji Sung said it did not bother him that other actors turned down the role before it was offered to him.

"I wanted to do this drama ever since I heard about the troubles it went through with casting," he said. "Then it came to me."

And the producers offered the female lead to Hwang Jung Eum, who starred with Ji Sung in the hit melodrama "Secrets." The team had proven chemistry but would they successfully revive that chemistry in such very different roles?

"Kill Me, Heal Me" subsequently killed it in the ratings as well as earning positive reviews for Ji Sung's work. "Kill Me, Heal Me" rated as high as 11.5 percent in viewer ratings whereas "Hyde, Jekyll and I" only reached as high as 8.6 percent for an early episode and then kept falling, reaching a low of 3.8 percent on March 4.

Whereas the combination of Han Ji Min and Hyun Bin might have initially been favored to win over the combination of Hwang Jung Eum and Ji Sung, that's not the way it turned out.

Which just proves that there is no predicting which dramas will be successful.