Stop that terrible relationship before the chainsaw starts.

With creepy darkness in their hearts, ice water in their veins, and snake-charming smiles on their faces, psychopaths who are currently fantasizing about cutting off your arms make up anywhere from 0.6% to 4% of the population. And interestingly, their brains look remarkably different from yours. Psychopathic encephalons have a smaller prefrontal cortex — the part that regulates behavior, impulse control, and planning — and a deformed amygdala, the seat of negative emotions like fear, guilt and sadness. Too bad you can’t see that, or we’d be helping a lot less mysterious men with combovers look for something in their windowless white vans …
However, you can ID a psychopath on a behavioral level, just in case you need to suss out whether their disarming charm and methodical dominance means they’re terminally cool, or currently plotting your death via chainsaw dropped down a stairwell. Here are five traits of psychopaths to look out for.

Fearless dominance
Psychopaths are so lucky. While the rest of us toil away in the throes of emotion, they enjoy a privileged existence free of fear, anxiety or guilt. These dead-eyed predators do whatever they want, whenever they want without the pesky hindrance of conscience, social consequences, authority figures or worrying about the well-being of others. They know the rules of society; they just don’t care.
Example: Humiliating their boss in front of the entire staff.

Remarkably charming and suave
Even though psychopaths and sociopaths are emotionally hollow, they posses a flooring amount of charm and gravitas. They have to; that’s how they prime people for manipulation. They might be unusually gracious and funny, and partake in what seem to be charitable or otherwise endearing acts of kindness — but inside, they know that doing this is this quickest way to earn trust and adoration.
Example: Making it seem like they’ve known you for years when you only just met.

No empathy
One of the most salient traits of a psychopath or sociopath is an utter lack of empathy. They can’t see a situation from someone else’s perspective, so they’re free from dealing with the pain they inflict on others. However, they understand emotion on a conceptual level, so they study it to learn how to act and what to say to get what they want. This trait makes them perfect dictators, serial killers and DMV employees.
Example: Well, killing someone would be a great example.

Extreme impulsiveness
The phrase “There is a time and a place for everything” does not apply to the psychopathic or sociopathic thought process. The act impulsively, with no regard for the fallout of such rash actions. They need a lot of stimulation and get bored easily, so they’ll do things like drive drunk, shoplift, start fights, humiliate coworkers, roofie that girl’s drink or torture animals just because YOLO. They’re also totally irresponsible. They don’t pay people back. They don’t go to work if you they don’t feel like it. They’ll walk out of a job, break off relationships and drop out of school with no warning because shit, they’re the next Hannibal Lecter.
Example: Cheating on you … with 14 people … in a week.

Low reactivity
A really interesting thing about that future Ted Bundy is that their physiology is different from non-psychopaths. Their resting heart rate is lower, their skin conductance is lower, and the beat-to-beat alterations in your heart rate are different from the portion of society who doesn’t eat from human-skull bowls. They’re eternally cool as a cucumber, even when other’s react, and they do their best work in a crisis situation. Rage is not a thing … Instead, their heart rates goes down when they’re in conflict.
Example: Winning a fist fight by using their terrifyingly calculated words, not arms.