Jack is the title character of the webcomic of the same name. He is a wizened green rabbit, wearing a ragged, brown cloak and most often seen carrying a scythe. He is the Sin Wrath and it is also his job to collect the souls of the dead and lead them to their final judgment as the Grim Reaper. He, along with the webcomic, is a direct ripoff of Spawn, in design, characters, and story. The most notable being the main villain Drip, who, in design, character, and contribution to the story is a direct ripoff of both Malebolgia and Clown/Violator.
Jack does not enjoy this duty, but it is apparently part of his punishment for sins committed when he was alive. Little of his past is known, as forgetting his past life is also part of Jack's punishment in Hell. Though he has stated he is blessed to not remember his life, he has sought out the help of the angel Farrago in restoring his memories. The only Sin who follows the rules, he is also the only Sin on reasonably friendly terms with the angels of Heaven, which changes for better or worse through events that happen throughout the comic.
In Hell, Jack takes care of the child Fnar, who considers Jack as somewhat of an uncle of his.
When Jack was alive he was part of a scientific experiment, part of which involved him meeting a female rabbit called Jill, and having no sexual organs. During this time, Jill was killed as part of the experiment, which made Jack wrathful, saying "She died, so I made me God!" although what he did exactly is unknown.
It could be construed that Jack and Jill were collectively the first anthropomorphic animals on earth, as the details of the scientific experiment involving him appear to be that rabbit/hare DNA was injected into an already fertilized human egg cell, which was then grown in a laboratory and resulted in Jack. He is referred in in the comic as being a Dictator, and it was he who decimated the human race and ushered in the 'furries' (as Dr. Kane once referred to them) as the ruling race of Earth. It has also been hinted that Dr. Kane was one of the human scientists working on the experiment that Jack was the control group for.
As the Sin of Wrath, he is quite quick to anger. However, since the sin is not usually associated with self-interest, he often does this out of more outgoing feelings, such as love. However, after absorbing Drip (Malebolgia and Clown/Violator), his brother sin Lust, into his being, his higher rage has become more common in tense situations.
Jack appears to be the strongest of the sins as shown when he becomes enraged. In this state(which the only physical trait different than his normal for being his eyes turning black) he has shown to be able to defeat Drip with ease. Drip hinted that Jack keeps his power down since he tries to suppress his sin (Wrath) while the others sins don't, this could be why the other sins don't appear to have this kind of transformation.
In the current arc all Jack's memory's were restored by Reckonin. It is however unlikely, that he will ask for redemption, since he already knows about his replacement.