One of the most fascinating things about "Empress Ki" is the character development. When a drama has 50 episodes, its characters have plenty of time to grow and change. And Ji Chang Wook's Emperor Ta Hwan may be one of the best character transformations in the historical drama.

Ji Chang Wook was not an unknown actor before he was cast as the emperor but this role has certainly boosted his popularity.

Previously, the 26-year-old actor was best known for his role in "Smile Again," which topped the ratings chart for 15 weeks, his role as the title character in "Warrior Baek Dong Soo" and playing a genius pianist in "Five Fingers."

But he really has been impressive to watch in "Empress Ki," even among the ensemble cast of talented co-stars.

Here's why we think his performance in this drama deserves an award.

1. He grows up before viewers' eyes. At the beginning of "Empress Ki" he is a spoiled immature prince. He's clever enough to survive an assassination attempt but he's basically scared of his own shadow. It is Seungnyang, played by Ha Ji Won, who teaches him to fight, both by showing him how to write and how to shoot an arrow. She helps him overcome fear. After all, once you've jumped off a cliff, what else is there to fear? Ji Chang Wook is very believable both as a scared little boy and eventually as a confident ruler.

2. When he confidently assumes power, he is a force to be reckoned with. Having been cowed for much of his life by El Temur, he overcomes his fear and takes command with authority. You can still occasionally read the vulnerability in his eyes, especially when he is jealous of Wang Yoo, but he has learned to be strong from Seungnyang and he means to exercise his power. He wants to be a man and a ruler she can be proud of.

3. He's a very romantic character delivering lines designed to melt the most jaded heart. Some of these lines might sound corny if spoken by a lesser actor, but the way he expresses his longing for Seungnyang rings very true. For example, when Seungnyang is vanquished to the Frozen Palace, he joins her for the night, telling her that his empty bed is like a bed of nails without her. Then he places his fur-lined royal cape around Seungnyang. It's not the first time a k-drama man leant a woman a coat, but since that coat is an Emperor's, the gesture is especially romantic. It is his love for Seungnyang that makes him a true emperor. And if there is anything Ji Chang Wook is good at, it's playing a man transformed by love.

Thanks to his memorable portrayal on "Empress Ki," Ji Chang Wook is an actor people won't easily forget.