Dream Flayers start out as tiny, ethereal insect-like creatures. They find a victim, and phase inside. Once in, the creature slowly takes over its host's dreams, turning them into nightmares. Soon, its influence is exerted during its victim's waking hours, inspiring fear, anger, and paranoia. The mental stress often causes the victim to begin acting suspicious, and even aggressive towards others. The Flayer feeds off of these negative emotions, and grows.

Adult Flayers can take on a large variety of insectoid forms, and are always considered very dangerous.