YMMV / The Gu Family Book

• Complete Monster: Jo Kwan Woong is an ambitious nobleman who destroys a man who was his friend and sends the man's daughter to be turned into a state gisaeng, or prostitute. He then attempts to rape her himself, stating that defiling her would be no fun if she didn't struggle, before discovering she has escaped. In retribution, he executes her brother and later engineers her betrayal of her Kumiho husband Wol-Ryung. 20 years later, Kwan Woong has a number of people in high level positions purged and murdered, and conducts a series of further murders, even killing the goodhearted Lord Park, brainwashing Park's son that it was his foster brother and raping Park's daughter. When Wol-Ryung returns as an amnesiac demon, Kwan Woong still comes off as the worse of the two by manipulating him for his own purposes. Even at the end, Kwan Woong confesses his actions were all to alleviate the tedium of life, with no remorse for his evil deeds.
• HoYay:
  • Tae-seo seems to have more than foster-brotherly affection for Kang-chi; Kang-chi is completely oblivious.
  • Yeo-wool's teacher is understandably scandalized when she walks in on Gon tearing through the sheets looking for Yeo-Wool. And a shirtless Kang-chi is lying in the same bed. It's Played for Laughs, and Yeo-Wool herself does manage to clear up the misunderstanding.
• Tear Jerker: This series can and will crush you emotionally.
  • Wol-Ryung's first death. After being betrayed by the woman he loved, all he can do is stare at her in heartbreak before pleading with her to tell him why. "I loved you. I loved you so much..." The look on her face is just as heartbreaking, as she's realized that the good man she fell in love with wasn't a lie after all, but by then it's far too late.
  • And later on, Seo-Hwa's Heroic Sacrifice to kill herself to reawaken Wol-Ryung's goodness. He finally remember the good person he used to be, and how much he loved Seo-Hwa. The first thing he sees upon his return to sanity is his beloved dead in his arms.
  • The death of Yeo-Wol, as she passes away in the arms of Kang Chi, the two desperately trying to pretend they're going to have the future together they longed for.