Reading Notes: Poisonous People by Leanne ten Brinke The book begins by introducing the four core traits of psychopathy: how psychopaths treat others, experience emotions, evaluate risk, and relate to social norms. Clinical psychopaths exhibit all four core traits to a pronounced degree. In contrast, people we encounter in everyday life may show one or more of these traits, but they are usually less severe, less balanced across the four dimensions, and do not meet the threshold for clinical psychopathy. To identify dark personality traits, the book suggests paying attention not only to nonverbal behavior but also to the way people speak. Stay curious, ask follow-up questions, and encourage them to elaborate on details. If you want to test the consistency of their story, avoid revealing information you already know. The book also introduces a screening questionnaire called the Dark Behavior Scanner. It helps us identify potential warning signs during everyday interactions. Finally, compare your observations with those of mutual friends whenever possible. Their perspectives may confirm your impressions or reveal biases in your own judgment. We may not be able to eliminate toxic people from our lives completely, but the book offers several practical strategies for dealing with them. It recommends setting clear boundaries, avoiding giving them authority over others, looking for win-win outcomes whenever possible, using rewards rather than punishment to encourage cooperation, strengthening a shared sense of identity, and favoring arrangements that leave a transparent, verifiable record. When necessary, it also suggests avoiding face-to-face negotiations in favor of written communication. Written communication gives us time to think carefully instead of being pressured by someone who is highly persuasive or manipulative. It can also reduce the risk of confrontation if the other person becomes aggressive. Most importantly, we should set realistic expectations. Personality is deeply ingrained, and meaningful change is both difficult and uncommon. Rather than trying to change toxic people, we should focus on protecting ourselves and responding to them effectively. At the end of the book, the author reminds us to remain kind, even when others are rude. She also encourages readers to rethink what success truly means. When choosing a leader, we should look beyond expertise and pay attention to how that person treats, works with, and communicates with others. Throughout the book, the author presents evidence that people with kindness, integrity, and strong character tend to build stronger relationships, achieve more sustainable long-term success, and ultimately create greater value over time. As the book repeatedly references Donald Trump as an example of these dark personality traits, I found myself thinking of another president who also seemed to exhibit many of these traits. The book reminded me that charisma and competence are not the same as character. It is easy to admire intelligence, confidence, or persuasive communication while overlooking how a person treats others. Going forward, I want to pay closer attention not only to what people achieve, but also to how they achieve it. Rather than judging people by first impressions, confidence, or isolated incidents, I want to evaluate them by consistent patterns of behavior and hold myself to the same standard. Looking back, I also realized how much our environment can shape our behavior. Factors such as sleep deprivation, chronic stress, poor air quality, or an persistent unpleasant odors can influence how people think, feel, and behave. In my own experience, I was often more irritable and prone to poor decisions when I had to work in offices where I was regularly exposed to second-hand smoke. I cannot say that it was the only cause, but leaving those unhealthy workplaces has made a noticeable difference to both my well-being and the way I respond to difficult situations.