De'fient is a corporeal demonic entity. The entity has no body but is decidedly male, even the entity itself has no idea how old he is or how he was created. As an entity he is trapped on the Earthly Plane through unknown means and for unknown reasons.
He lives off of the corruption of human souls, particular taking an innocent human girl and corrupting her until either she dies or manages to sever her link to him.
Age / Origin
De'fient is so old he no longer remembers where he came from or how long he has been here. He sleeps for vast periods of time floating unseen through the Earthly Plane of existence.
Choice / Binding
Through whatever means he can, he must persuade a person to allow him into their minds and thus bind to their souls. The process of binding to the soul of a person takes time, it can be a very slow process or sometimes, if the person opens up completely, can occur within just a few days. During this time, De'fient must convince the person to let him inside, allow him to bind to them - though he may not get direct permission, simply allowing his contact and influence for long enough will allow him bind to her.
Corruption
His consumes the darkness that comes off of human souls as they become corrupted. The longer he can maintain a human soul in his power without that soul passing out of this plane of existence, the longer he is nourished and stays awake and alive.
Sexuality
While the corruption of a human soul sounds decidedly sexual, and De'fient does prefer such corruptions, they are not the only ones available. Any darkening of a human soul will do to serve his needs. He need not pressure a soul into sexual acts if acts of monetary, ethical, or other natures will serve to bring darkness into the soul.
Protection / Obsession
He is intensely protective of the soul he is bound to, and seeks to preserve that soul at all costs.
Physical Form
De'fient can take physical form for limited spans of time, but it is costly to him. Often after taking a form for several hours he must withdraw and sleep, becoming dormant, for a span of days proportional to how long he lasted in physical form. He can also take form only for his bound soul, so that she is the only one who can feel or see him.