Character Arc
Yi San is the Crown Prince of Joseon and the future King Jeongjo, introduced as a disciplined, intelligent young royal living under intense political pressure. Haunted by the death of his father, Crown Prince Sado, and surrounded by court factions that view him with suspicion, Yi San learns early to guard his emotions and calculate his every move. Beneath that composure, however, lies a steadfast and deeply human capacity for love.
His feelings for Seong Deok-im form across years of proximity, and the drama treats his devotion as patient rather than possessive. Repeatedly, he offers her elevation and is repeatedly, gently refused; rather than forcing the issue, he wrestles with the gap between what he wants as a man and what he owes as a sovereign. This restraint, and the quiet respect he shows for Deok-im's wishes, became one of the most discussed aspects of the series among viewers.
As he ascends to the throne, Yi San must reconcile the burdens of kingship, including reform, governance, and survival, with his private heart. The role earned Lee Jun-ho the Baeksang Arts Award for Best Actor (Television), a milestone widely noted for an idol-turned-actor, and cemented the character as one of the defining romantic leads of modern sageuk.