(In fact, the contagiousness of toxicity is a natural defense mechanism. Howard Bloom in
The Lucifer Principle explains how increased toxicity of cyanobacteria was one of the first evolutionary adaptations — bacteria actually evolved to get more and more toxic in order to survive. The same applies to humans on the macro level.) And more of than not, the pattern happens without us even realizing. If you’ve ever had a toxic boss, then you know how this works: