Hazbin Hotel and Helluva Boss are set in a Dante inspired depiction of Hell, which draws from the Torah and Talmud, particularly the writings of King Solomon and Daniel.
In the beginning, there was Heaven, a domain created by the divine in isolation from the influences of evil. In Heaven, the seraphim were given the task of creating the realm of Earth, and all the heavenly bodies that surround it. Upon the Earth, the seraphim created two intelligent beings, the man Adam, and the woman Lilith.
Adam, convinced of his own superiority, demanded that Lilith be subordinate to him in all things. Lilith refused, and left Adam alone in the garden of eden. In response, the Seraphim created Eve, a second woman, formed to be the subservient figure that Adam wished, lacking her own free will.
A member of the Seraphim, Lucifer, who had been discontent with the despotic ways that his rank formed the universe, saw Lilith as a kindred spirit, and sought her out. Together they conspired to give Eve the gift of knowledge of good and bad, restoring her freewill and freeing womankind.
This act of disobedience fractured the isolation of Heaven and Earth, allowing the forces of evil to enter the domain. In response, the seraphim cast Lucifer out of Heaven, tasking him to create a new realm to contain the various denizens of evil that his actions had allowed into this domain. Together, Lucifer and Lilith created Hell. As humans perished, those souls who had been influenced towards evil would be sent to Hell to become demons, and those who remained pure would ascend to Heaven to become angels.
Hell is divided into seven layers, connected by elevators, with each layer formed of nine concentric rings. The layers are, ostensibly, governed by each of the Seven Deadly Sins: Lucifer (Pride), Satan (Wrath), Beelzebub (Gluttony), Mammon (Greed), Asmodeus (Lust), Leviathan (Envy) and Belphegor (Sloth). Hell also has several royal families, including the Ars Goetia, formed by the original demons which entered the domain when Eve ate the apple. These families rule over the lesser hellspawn, such as Imps, Hellhounds, and Succubi.
Helluva Boss depicts the lives of the lower layers of hell, centering on a group of imps (and one hellhound) led by Blitzo, a former circus clown turned assassin. The series depicts the lives of the various hellspawn and examines the dynamics of the social order within Hell.
Ten thousand years after the corruption of Eve, fearing that Hell will become overpopulated with the souls of human sinners, and rise up against Heaven, Adam convinces the Seraphim to allow him to conduct an annual culling of sinners. Armed with angelic steel (the only weapon capable of permanently harming a demon), Adam leads an army of exorcist angels into Hell to exterminate anyone they come across.
Hasbin Hotel opens in the aftermath of one such extermination event. The series depicts the lives of sinners, the human souls cast down from earth. It centers around Charlie Morningstar (daughter of Lucifer and Lilith), and a group of sinners that she has enlisted in her effort to rehabilitate the damned and halt the exterminations.
The series explores what it means to be good and evil, and questions the very foundations of religious dogma.