- Complete Monster: Gwi is an evil vampire who was once promised dominion over the night in return for helping the king rise to found his dynasty. Gwi lurks in the palace, preying upon the innocent and killing them as he wishes. When one prince tries to oppose him, Gwi murders him and his own former teacher who has arrived to stop Gwi. When this teacher turns a young scholar into a vampire, Gwi causes the death of the man's lover and the two enter into a 120-year conflict where Gwi tortures and murders another prince, uses innocents as bait to draw his rival out and has suspected collaborators tortured. When he grows sick of hiding in the shadows, Gwi declares himself king and turns multiple people into vampires so they will lead attacks on and kill the innocent, whereupon Gwi will heroically ride in and save the day so the people will adore him. When this fails, Gwi simply attempts to destroy everything he can. Utterly lacking in humanity, and responsible for at the very least several hundred deaths, Gwi is a vicious predator who relishes his monstrous nature.
- Mind Game Ship: Gwi/Hye Ryung is a canon example. "Messed-up" doesn't begin to describe their relationship (she serves him only because her father made a deal with him, and he threatens and manipulates her). But Gwi appears to genuinely regret killing Hye Ryung, even telling her corpse that he wanted to keep her by his side for thousands of years. Though he also says he wanted to make her hate him, so it's open to interpretation if he had any real feelings for her or if he just enjoyed making her miserable.
YMMV / Scholar Who Walks the Night