Lucifer is nominally the ultimate antagonist of the webcomic 'Jack'.
Appearance
Since he is an expy of the comic writer's fursona, he usually appears as a humanoid blue skunk; he is always depicted wearing a gray, full-body robe. His appearance is disheveled and worn-out; he seems bent-over with age. His eyes are completely black, a trait he shares with Jack's version of God.
Characteristics
According to God, Lucifer once loved music. Nominally pure evil, Lucifer is usually affable, cheerful and sarcastic; he will tempt people into their doom, but either cannot, or won't, push them over the boundary; they have to step over it themselves. He taunts and torments the damned, even the Sins - damned souls who possess demonic power because they embody one of the Seven Deadly Sins - and conspires to keep them in Hell for as long as possible (for in 'Jack', it is possible, seemingly even inevitable, for people to eventually escape damnation) but the innocent and heroic find a measure of mercy in his eyes. He seems to be working towards retiring and manouvring someone else into his position as Hell's ruler.
History
In the void before existence, Lucifer - not yet fallen - suggested that something should be created, and God agreed, deciding to create the Universe. As the design developed, Lucifer grew worried; about humanity, its potential to hurt itself without the innate knowledge of God he and the other angels had, about it being tempted by the Tree of Knowledge of Good and Evil; and about eventually being replaced by humanity. At an unknown time after Creation, Lucifer rebelled against God along with an unknown number of other angels, and was banished to Hell - not for all eternity, but 'until he's ready to say sorry' (which, of course, still may mean for all eternity). There he now rules, from the very deepest point of Hell, often venturing out into his kingdom to torment some particularly vile soul.
Powers and abilities
Within the confines of Hell, Satan's power is absolute; the damned are subject to his whims, and even the powerful Sins are just pawns in his schemes. He can change his own appearance, appearing once as a human, another time as a terrifying dragon. He can appear in the mortal world, seemingly speaking through people in a kind of temporary possession, to tempt others into doing evil.