My Demon - Characters & Cast

His primary motivation is survival. Initially, he must protect Do-hee to preserve his own life and powers. This selfish goal slowly transforms into a genuine desire to protect her for her own sake. As he falls in love, his motivation shifts entirely to ensuring her happiness and safety, even at the cost of his own existence. He is also haunted by the memories of his past life as a human, Seo Yi-sun, and the tragic death of his lover, which drives his fear of history repeating itself.

Initially, Jeong Gu-won is a narcissistic, cold, and powerful 200-year-old demon who views humans as insignificant. His entire existence is based on transactional deals for souls. After losing his powers to Do Do-hee, he is forced into a state of vulnerability for the first time in centuries. His arc is a journey of rediscovering his lost humanity. Through his contractual and eventual real marriage to Do-hee, he learns empathy, love, and selflessness. He transforms from a predator into a protector, culminating in his ultimate sacrifice: choosing to cease to exist in order to save her life. His resurrection by a deity doesn't revert him to his old self; instead, he embraces his love for Do-hee, choosing a finite, meaningful existence with her over a lonely eternity.

Initially, her motivation is to survive the attacks from her adoptive family and secure her position as the heir to the Mirae Group. She enters the contract marriage with Gu-won as a strategic move to gain a bodyguard and a stable position. As her feelings develop, her motivation shifts to protecting Gu-won and building a genuine life with him, valuing their relationship above the corporation and her own safety.

Do Do-hee begins as a guarded, cynical, and emotionally distant CEO, hardened by the loss of her parents and the treacherous environment of her adoptive family. She trusts no one and is entirely focused on her work. Her involvement with Gu-won forces her to open up and rely on someone else. Her arc is about dismantling the emotional walls she built for protection. She evolves from a lone survivor into a person who can love and trust deeply. She proves her strength not just in the boardroom but through her emotional resilience, facing down assassins, corporate enemies, and supernatural threats, ultimately willing to make a deal with God herself to bring back the man she loves.

His core motivation is his deep-seated, albeit platonic, love and concern for Do-hee. He wants to protect her from the dangers within their family and from the mysterious Gu-won, whom he initially distrusts. He investigates Gu-won's true nature not out of malice, but out of a desire to ensure Do-hee is safe. He eventually accepts their relationship and channels his motivation into supporting them both.

Joo Seok-hoon is introduced as the nephew of the Mirae Group's chairwoman and a potential rival or antagonist to Do Do-hee. He is the CEO of Mirae Investment and appears to harbor unrequited feelings for her. For much of the series, his actions are ambiguous, making the audience question his loyalty. However, his arc reveals that his primary concern has always been Do-hee's well-being. He evolves from a quiet observer and potential threat into a loyal ally and friend to both Do-hee and Gu-won, ultimately taking over as Chairman of Mirae Group to support her. His journey is one of clarifying his intentions and finding his own place outside the shadow of his family's drama.

His sole motivation is to gain complete control of the Mirae Group. He believes he is the rightful heir and will eliminate anyone who stands in his way, including his family members. His actions are driven by a profound sense of entitlement, greed, and a complete lack of morality.

Noh Suk-min is the eldest son of the Mirae Group's chairwoman and the primary antagonist. He starts as a seemingly legitimate contender for the company's inheritance but quickly reveals his ruthless and violent nature. His arc is a descent into pure villainy. He is revealed to be the murderer of his own mother and the mastermind behind the attempts on Do-hee's life. He is an abusive husband and father, driven by an insatiable greed for power. His character does not evolve but rather devolves, losing his sanity and ending up imprisoned and haunted by his mother's ghost, a shell of the powerful figure he sought to be.