Violent and aggressive behavior is characterized by hostile, intimidating, and destructive actions. FIERCE is an adjective that describes this type of behavior, which can range from physical aggression to verbal abuse. It is often used to describe people who are prone to outbursts of anger or violence. FIERCE behavior can also be seen in animals, such as when a predator is hunting its prey. In either case, it is a behavior that is meant to intimidate and cause fear.