I actually needed to think for a while until I decided on the rating. There are things that brought me so much enjoyment in this drama, so many screencaps spamming my mdl friends with (I apologize couldn't help myself:D) but there are some things that annoyed me as well, or that I didn't enjoy, or found useless, or even wished it was written out of the story, even if that would shorten it to a 12 episodes drama. There is two sides to the story. There is your typical chaebol family with their problems and struggle to inherit the company, then there is also the side of the character dealing with a multiple personality disorder meeting a cheerful normal girl, who belongs to a cheerful normal family. The way that lovely family is so perfectly portrayed, and how fun it was to have them on screen, makes me wonder why koreans are so obsessed with chaebol stories. In any case when I look at it in that sense, the story isn't original at all, and I find the disorder was used as a trope rather than being the central key to the story. The reason is, we don't see any real treatment to it, though we do deal with the past, but realism wasn't what the drama was going for. That did not bother me because it made the characters of this drama original, changing the dynamic this drama would've taken otherwise. The acting is what elevated this drama, made it not only watchable, but one of the most anticipated dramas for me this season. I am ashamed to admit it is my first time watching a Ji Sung drama, and oh boy, saying I'm impressed is an understatement. His distinct portrayal of each personality striking. He had full control of the look in his eyes, his voice, and every nerve forming his facial expression. Then there is Park Seo Joon who is also my first time seeing. He is one of the best his generation, and I'm pretty sure his future is already set. As a loser son, as an amazing brother, as a mysterious writer, and a haunted individual with a bit of darkness, he depicted so many sides of his character you'd this he's the one with the disorder lol. Hwang Jung Eum might've understandably annoyed many viewers but she didn't bother me. I think it's because her character is so frank that I can forgive anything. I liked her in the serious scenes more though. The actors playing Ri Jin and Ri On's parents were also fun, and very natural in their role. Specially the mom always expressing her love, fear, expectations and pride through her facial expression. Choi Won Young as secretary Ahn was also fun. his role was straightforward that I don't think he was required anything more, but he did manage his comedic moments throughout and that I appreciate. Last but not least, the children were also really good in their role. As for the rest of the cast, they might've been good but I didn't notice, because I didn't care and mostly was skipping their scenes. Thankfully the actors/characters mentioned above were onscreen mostly. I really appreciate the direction here, many things were handle impressively, but some things started annoying me later on in the series. I like the effects used, when blurring the line between reality and illusion. I also really love the effective use to light here. I think it helped Ji Sung in portraying his characters. Basically each of the personalities had a specific light and colours used, emphasizing on their character but sublte enough to not disturb the whole scene. The choice of music was also great and effective, especially that theme song ?? (Auditory Hallucination). I do have a complaint though with this department. The amount of flashbacks used in the last 6 episodes could fill two complete episodes. The same goes with the dragged out scene of a brooding character for the sake of finishing the song. It felt really inefficient and draggy. I am happy that they used this way to drag out the episodes instead of using writing unnecessary events to drag out the story. Still I would prefer that a drama cuts out everything that makes it boring and draggy. As for the ending, it's hard for me to say if I was overall satisfied or not. The part that I fully enjoyed in the story had a well written and extremely satisfying ending, the side that I didn't enjoy had an even worse ending. I put a high rewatch value only because I think it'll be fun to go back and watch the personalities of Ji Sung and watch Ri On and Ro Jin bicker, although I wouldn't attempt the whole drama a second time. To summarize my thoughts, the story itself is actually is actually generic, while the themes and tropes used are original. The main characters are different, written with depth and insight and the acting was through the roof. It was highly entertaining and did not let the melo side drag it down.