Watch out for Vulcans

Highly emotional people may seem wildly unconstrained, but they are not. Well-accustomed to emotionality, they preserve some shred of control and restraint in the midst of explosion or collapse.

By contrast, people who feel they possess complete emotional control are dangerous because we can't constrain what we don't recognize. Such a person might crush your skull over some triviality because there's no ongoing measured process of ascertaining proportionality—or any other sort of measuredness when it comes to emotions.

Those who fashion themselves evolved beyond emotion are actually emotionally stunted, so when emotions do arise, they're like daggers wildly projected from subconscious viscera.