They are errant thoughts of Terminus. Idle curiosity and intense desire made flesh. Awakened dreams forced into painful consciousness. The mind of the wanderer freed from the body. They are the alratheen.
Alratheen are literally the mind of Terminus. Their bodies are the neural structures of the sentient, slumbering plane. Birthed deep within the bowels of Terminus, the alratheen are the network that houses the consciousness of the plane.
Not all alratheen remain at the core of the plane. Some alratheen are created to perform specific tasks, such as the policing of other creatures found on Terminus or exploration of other planes. The purpose of other alratheen is less specific. These alratheen are physical manifestations of stray thoughts of Terminus.