The Darkness is a purely malevolent demonic entity and is clearly a sociopathic creature which only gets pleasure from Jackie's negative emotions and violent acts he commits as its host. The entity is extremely cunning and violent.

Powers include Immortality, Resurrection, create anything out of darkness

Weakness is light, Human Dependence, and Host Rejection.

Enemy of the light/Angelus.

Eats hearts to heal faster.

Appearance as two elongated serpent like tendrils of darkness with red eyes and sharp teeth extending from host’s back, but only when let out.

It also has a sadistic personality, taunting and insulting its hosts as well as tormenting and violently executing its enemies.