What's Wrong with Secretary Kim — Ending Explained

The Identity Twist: Throughout the first half of the series, Young-joon's older brother, Lee Sung-yeon, claims he was the child kidnapped decades ago and blames Young-joon for leaving him. In Episode 11–12, it is revealed that Lee Young-joon (born Lee Sung-hyun) was the actual victim.

The Origin of the Brother's Delusion: As children, Sung-yeon left young Young-joon behind in an unfamiliar neighborhood out of jealousy, leading to Young-joon's abduction. Overcome with unbearable guilt when Young-joon returned traumatized, Sung-yeon's mind created a defensive delusion where he was the victim.

Young-joon's Sacrifice: Young-joon pretended to lose his memory and adopted a new legal name (Young-joon instead of Sung-hyun) so his family would not break apart under the weight of his brother's psychological breakdown.

Why Young-joon Hired Mi-so: Young-joon never forgot Mi-so. Nine years prior to the series, he specifically sought her out and hired her as his secretary to quietly look after her and compensate her for the horror they shared, waiting until she was ready to remember.

The Finale: After overcoming their shared past, Young-joon and Mi-so hold a magnificent wedding. Mi-so chooses to continue working as Vice Chairman Young-joon's secretary out of personal love and professional pride.

Psychological Reading (Narcissism as Trauma Defense): Under a psychological lens, Young-joon's grandiosity is not genuine vanity, but a survival strategy. Having carried the horror of the kidnapping and the burden of faking amnesia to keep his older brother from psychological collapse, his ego became a fortress. His obsession with Mi-so stems from her being the only living witness to his unmasked trauma.

Feminist vs. Traditional Reading (The Choice to Stay): Critics and viewers have debated Mi-so's choice at the end of the series. The traditional/feminist critique argues that having Mi-so remain a secretary to her CEO husband after regaining financial freedom undermines her journey toward independence, reducing her back to a supportive role. Conversely, the agency/self-determination reading asserts that true empowerment lies in choice. Mi-so's decision to stay is empowering because she stays on her own terms, out of genuine passion for her profession and love for her partner, rather than financial desperation.