All the characters in this drama were full of flaws but I don't think they were "born" with evil roots but rather greed and circumstances changed and drove them to pursue the unthinkable repeatedly and relentllessly until the point of no return. Some characters started out innocent but because of personal harship, revenge, inferior complexities etc, majority of them went all out to hurt others with only a handful would reflect, regret and repent. What bothered me most was how each and every one of them was able to find reasons and excuses to justify their own wrongdoings. In the end it was all this wrong justifications that led them to self-destruct and death.
While Soo Ryun finally succeeded in killing her mortal enemies to avenge her daughter's death, she could not accept the lives she had sacrificed, to achieve this goal. She probably also felt guilty and unable to face her children being the perpetrator who ultimately killed Seok Hoon's father. And I guess this justified the bittersweet ending....
There were other things I could not digest because they made no sense in reality: 1. Cheon Seo Jin was the head of Cheong-A Group/Academics BUT SHE WAS also a parent of one of the students YET she was constantly participating in class exams or singing contests either as a judge/invigilator. The parents and residents of Hera Palace were always good at protesting at everything so why can't they just band together and stop her from conducting these activities? In reality a person that holds a significant position but has conflicting interest in that matter should remain impartial and delegate responsibilities but she was in the front and center of everything and that's why there were so many corruptions going on. 2. Joo Dan Tae and Cheon Seo Jin giving up money so easily towards the end just to appease Baek Joon Ki and Jin Bun Hong from harrassing them when based on their negative character development throughout the entire series, they could senselessly murder, threaten or torture those two. 3. I also found it amazing how Logan could withstand the pain of being scalded with hot boiling water without even flinching. It's not like he was heavily drugged or sedated either. And in almost the next episode that followed after, he could walk without limping!! And not to forget, it was a miracle indeed how he survived a bomb which exploded right next to him but only ended up with minimal burnt wounds and scars??
News 
Some characters started out innocent but because of personal harship, revenge, inferior complexities etc, majority of them went all out to hurt others with only a handful would reflect, regret and repent. What bothered me most was how each and every one of them was able to find reasons and excuses to justify their own wrongdoings. In the end it was all this wrong justifications that led them to self-destruct and death.
While Soo Ryun finally succeeded in killing her mortal enemies to avenge her daughter's death, she could not accept the lives she had sacrificed, to achieve this goal. She probably also felt guilty and unable to face her children being the perpetrator who ultimately killed Seok Hoon's father. And I guess this justified the bittersweet ending....
There were other things I could not digest because they made no sense in reality:
1. Cheon Seo Jin was the head of Cheong-A Group/Academics BUT SHE WAS also a parent of one of the students YET she was constantly participating in class exams or singing contests either as a judge/invigilator. The parents and residents of Hera Palace were always good at protesting at everything so why can't they just band together and stop her from conducting these activities? In reality a person that holds a significant position but has conflicting interest in that matter should remain impartial and delegate responsibilities but she was in the front and center of everything and that's why there were so many corruptions going on.
2. Joo Dan Tae and Cheon Seo Jin giving up money so easily towards the end just to appease Baek Joon Ki and Jin Bun Hong from harrassing them when based on their negative character development throughout the entire series, they could senselessly murder, threaten or torture those two.
3. I also found it amazing how Logan could withstand the pain of being scalded with hot boiling water without even flinching. It's not like he was heavily drugged or sedated either. And in almost the next episode that followed after, he could walk without limping!! And not to forget, it was a miracle indeed how he survived a bomb which exploded right next to him but only ended up with minimal burnt wounds and scars??