To switch effectively from defense to social engagement strategies, the nervous system must do two things: (1) assess risk, and (2) if the environment looks safe, inhibit the primitive defensive reactions to fight, flight or freeze.

Playing nice" comes naturally when our neuroception detects safety and promotes physiological states that support social behavior. However, pro-social behavior will not occur when our neuroception misreads the environmental cues and triggers physiological states that support defensive strategies. After all, "playing nice" is not appropriate or adaptive behavior in dangerous or life-threatening situations. In these situations, humans - like other mammals - react with more primitive neurobiological defense systems. To create relationships, humans must subdue these defensive reactions to engage, attach, and form lasting social bonds. Humans have adaptive neurobehavioral systems for both pro-social and defensive behaviors.

The detection of a person as safe or dangerous triggers neurobiologically determined pro-social or defensive behaviors.
Even though we may not always be aware of danger on a cognitive level, on a neurophysiological level, our body has already started a sequence of neural processes that would facilitate adaptive defense behaviors such as fight, flight or freeze. 

A child's (or an adult's) nervous system may detect danger or a threat to life when the child enters a new environment or meets a strange person. Cognitively, there is no reason for them to be frightened. But often, even if they understand this, their bodies betray them. Sometimes this betrayal is private; only they are aware that their hearts are beating fast and contracting with such force that they start to sway. For others, the responses are more overt. They may tremble. Their faces may flush, or perspiration may pour from their hands and forehead. Still others may become pale and dizzy and feel precipitously faint.

By processing information from the environment through the senses, the nervous system continually evaluates risk. I have coined the term neuroception to describe how neural circuits
distinguish whether situations or people are safe, dangerous, or life-threatening. Because of our heritage as a species, neuroception takes place in primitive parts of the brain, without our conscious awareness.

What’s the worst thing I’ve stolen? Probably little pieces of other people’s lives. Where I’ve either wasted their time or hurt them in some way. That’s the worst thing you can steal, the time of other people. You just can’t get that back.