If you really have much exposure to novel reading, you'd realize good drama writing always starts with critical implication - or prediction from the very beginning. Remember in the first episode Xiamo saying something like "When Lou Xi first time showed up, I knew he's a predator." This indeed a very important implication. I never read the book. But if this was adopted from the book, I think the author meant what it was to be meant. Lou Xi's character is charming but aggressive somehow. I do not agree Ouchen is darker than Lou Xi. Just to the opposite. Let's wait and watch if he's going to reveal his darker side.