Once again, the content from this entry is heavily edited and expanded upon from the ENWorld forums. However, like the last post it does have new information, and is worth another go-over even if you've read the ENWorld posts. Thank you for your patience, and be comforted in the knowledge that there is only one more post like this planned, and then it will be entirely new content again!
Whenever a soul is traveling through the Inbetween, or astral-projecting themselves (safely) into the Astral Sea or another creature's dream, they do so using an astral body. An astral body is created from nothing, and normally reflects the soul's self-image, carrying with it astral constructs of any clothing or equipment that soul expects to have. A character with both an exceptionally high perception and willpower can create new tools and items for itself out of nothing - though the more powerful the creation the more difficult it is to manifest.
Creatures who are dead and carried to the nine planes of hell also use astral bodies, but they are under slightly different rules - the demons have organized it so that the willful creation of objects is no longer possible. Demons and the inhabitants of hell also can tell the difference between an object (such as money) that has been created willfully, and an object that was legitimately created by demons. This helps to stabilize the local economies of the Nine Hells.
The only exception to this rule is the Hell of Meh, where visitors have their astral body and all equipment stripped from them completely.
With an astral body, characters can do all of the things that they did in life, such as eating, sleeping, having sex, and even dying. Many of these activities do not work exactly as they do in the real world, however. Eating is not actually a requirement of astral bodies. Hunger is only felt by souls in astral bodies if those souls believe they -should- become hungry. Over time, many souls in hell lose the habit of eating, as they slowly realize their hunger will abate even without food. Others turn eating into a recreational hobby, and food is often provided by the demons themselves if the local ecology of a plane of hell cannot meet the demand.
Sex occurs in the afterlife just as commonly as it does in the material world, but astral bodies are all barren and cannot reproduce - with the exception of an astral body mating with a demon. A male astral body can impregnate a female demon, and a female astral body can be impregnated by a male demon. If the owner of the astral body is still alive, and returns to the world of Aarn while impregnated, the demon will still come to term - but psychically, connected to the female mortal's mind. Once the demon is ready to be born, other demons will possess the female in order to rescue the child, usually without the female ever knowing.
When it came to an astral body's inability to have children under normal circumstances, the demons were flooded with a great deal of hate mail and feature change request forms. As a result, the demons decided to allow souls who had been stillborn or died at a very young age to come to the afterlife in that form and then be adopted by waiting families. These souls could be considered very unlucky. They not only have to wait a hundred years or more in the demonic sub-plane of Immigration, but they are then put in a demon adoption agency where the wait for adoption can be even longer. Once adopted, their astral body will slowly mature to the height of adulthood. Once adulthood is reached, their astral body ceases to age at all.
Sleeping, unlike eating, is not something that is optional for astral bodies. The vast majority of mortal souls require dreams in order to maintain their sanity. Simply being dead is not enough to lift this fundamental requirement of mortal minds, and in fact, the lack of being able to dream is the major source of insanity in noncorporeal undead trapped in the Inbetween.
Dead souls in the Nine Hells do still dream in the astral sea, as they did when they were alive. During the deepest stages of sleep, a soul's astral body seems to dissolve into nothing. In actuality, it has been transported with the soul to that soul's dream pocket in the astral sea. When the dream is over, the soul is automatically transported back to its place in the Nine Hells.
Death in the afterlife is caused by an excess of trauma dealt to an astral body, and lasts only a fraction of a second, with a new astral body forming next to the newly-created corpse. In the Inbetween, the Astral Sea and dreams, this new body will normally have its equipment and belongings as well - which can create duplicates of astral items. In these same places however, a slain astral body will quickly fade to nothing, which makes the window for collecting these items very small. As a further risk, if the concentration of an astralmancer is broken, it can be extremely dangerous to all involved in the astral travel. Further, if it is a wizard or divine caster allowing the astral travel, the death of an astral body will normally break the spell before a new astral body can be formed, and return that person's soul to their real body.
Due to the limitations on astral object construction in the Nine Hells however, a slain astral body is permanent, as is its equipment. The new, healthy astral body that forms after a death will be nude and without any equipment. In planes such as anarchy or paranoia, cannibalism is rampant due to the excess of corpses that develop as astral bodies die and reform.
Astral bodies heal quickly from general injuries, but not as quickly as they would “heal” from a complete death and reformation in one of the hells. This has the interesting dynamic of forcing combatants in the Nine Hells to attempt to deal nonlethal blows – it is much easier to recover from death than it is to recover from unconsciousness.
There is an appeals process set up in the Nine Hells that allows someone to ask for adjustments to be made to their afterlife. Naturally, this appeals process takes a very very, very long time, due to the high number of souls who are miserable. Some of these appeals involve changing the appearance or structure of a soul's astral body. They can choose their apparent age, so those who have a fetish for age can appear old and wizened. They can also change their gender, or even their species. For instance, many dragons who wind up on the plane of Bureaucracy will often choose to appear as demons, and in fact, actually do become demons, both physically and spiritually.
Not only can souls in hell appeal for a change to their astral bodies, but they can also appeal their judgment. In fact, the vast majority do. The long wait for the appeal to be processed however forces the soul to stay in their initial judgment plane for thousands of years. Being forced to experience their supposed value system for that long often causes them to become tolerant of it, reinforcing that value system. When they are re-judged during their appeals process, they often wind up being sent right back where they came from.
Others however, instead learn to hate their original supposed value system, and when their appeal goes through, they have accumulated the wisdom, experience, perspective, and maturity for the demon judgment to actually work for once, and send them to a hell where they belong and would enjoy.
The least lucky souls are ones who do not learn experience and perspective through their suffering, and instead experience a "grass is always greener" effect. They wind up being sent to a hell during judgment that they hate even more than the place they came from. Especially obtuse souls wind up bouncing around the different layers of hell for much of eternity.
As an alternative for appealing their judgment, souls can instead send in an appeal form requesting to rejoin the One Mother as originally intended. Despite the shattering of the original gnostic cycle by Nektos' mischief, very small amounts of souls at a time can still do this. Though the feature was disabled for the past 50 years, the One Mother's reappearance has made it possible again.
The process is one that strips the soul of all memory of their current life and identity, though the resulting consciousness can spend the rest of its existence as a true part of the One Mother's soul, experiencing a kind of parasitic bliss. Despite the suffering souls undergo in the Nine Hells, the idea of losing one's own identity is something the vast, vast majority of souls find horrifying. Many consider it to be a true death. Because of this, the wait for rejoining the One Mother is quite short, and souls often wind up rejoining the One Mother as soon as a few weeks after they send in their appeal.
Another option for souls who wish to leave the Nine Hells is reincarnation. The reincarnation itself is handled by the One Mother, and the first step of it is rejoining her, in the same way as a soul who wishes to rejoin with her permanently. While memory, identity and experiences are still obliterated, the reincarnated soul carries with it a small imprint that allows the soul to identify its past lives in subtle ways. Unfortunately, a soul cannot request the type of creature it comes back as. The creature the soul is reincarnated into is chosen by the One Mother. Not surprisingly, this option is even less popular than rejoining her permanently, and is normally reserved for non-sentient animals.