Nightmare

Born from the mingling of dreams and fears, nightmares spring forth from the Ether, shaped by the darkest of mortal dreams. Born of fear, nightmares are sustained by it, planting the same seed of terror that gave birth to them in the fertile soil of sleeping minds, feeding of the resulting distress.
But the fear thus gained is, in a way, diluted, thinned by the barrier between worlds. So some nightmares seek to slip through the veil, using dreaming minds as a gateway, to spread fear among the spheres. According to nightmares, fear gained from a person is an incomparable rush and many begin exclusively feeding that way.
This sort of predatory behavior does inspire reprisals, but nightmares are equipped to fight. As long as they can feast of their enemies' fears, they can be near indestructible. Their twisted forms also gives them access to many powers and options, which can very hard to predict.

Basic Information

Anatomy

Nightmares are highly diverse and come in many forms.  There are some commonalities though. Due to being composed of thoughts, nightmares are less physical, which gives them protection from physical attacks, occasionally even allowing them to phase through attacks completely. They also don't feel fear, being nourished by the emotion instead. In fact, being near someone else feeling fear only empowers them. Finally, they can bind themselves to the mind of a person, sustaining themselves off that person's nightmares. As long as that person lives, the nightmare can never be truly slain, instead being reborn in the Ether if killed.

Genetics and Reproduction

Nightmares appear fully formed in the Ether, born from intense negative dreams.

Ecology and Habitats

Nightmares live in the Ether, feasting off the fear generated from bad dreams. They can also slither over into spheres through the dreams of mortals to sow fear directly, which is described by them as being the greatest of feasts.

Dietary Needs and Habits

Nightmares are emotivores. Specifically, they feed of fear, either passively through bad dreams or by actively scaring people.

Additional Information

Social Structure

Nightmares have incredibly varied social interactions. Some are pack hunters, others solitary terrors.

Geographic Origin and Distribution

Nightmares are native to the Ether, but they can manifest among the spheres wherever sleeping minds can fear.

Average Intelligence

Nightmares combined predatory instinct with sharp intelligence, allowing them to manipulate events to induce the most terror possible.

Perception and Sensory Capabilities

Nightmares may have any number of senses.

Civilization and Culture

History

Nightmares take names from the culture that helped birth them. These names usually have vicious or terrifying connotations.

Scientific Name

Somnum Exterreri

Lifespan

Does not age

Average Height

Varies depending on subspecies

Average Weight

Varies depending on subspecies

Average Length

Varies depending on subspecies