Cassiel is a feral-like demon, but he is as intelligent and can speak as well as any human-like demon.
He calls himself Cassiel, named after the archangel of solitude, because his favorite 'meals' come from the fears of being left alone. Loved ones dying, friends leaving, and never finding a romantic partner.

He feeds of of anxieties and stress given off by humans, making himself look moderately cute in his passive state to get people to believe he is friendly.
During his active state he will emit a red smoke from his mouth that triggers intense feelings of fear, often leading to a panic or anxiety attack.
When hungry, Cassiel will begin to become more and more agitated if he does not get a decent meal. He will become violent, speaking to his subject in a negative and aggressive manor. This tends to make the subject suicidal. (similar to the voice in a persons head.)

Cassiel will often follow humans whom are under a lot of stress or have mental disorders due to the fact they can make an easy meal.