The Power of Life
The Nine Heavens were set up to filter the ambient magic of life its normal progression to and from the source of magic, to take the magical power within the soul and feed it to the aedra who watched over the Heaven that it passed through.
The Power of the Afterlife
There are two layers to the afterlife in the world of Metamor: the Nine Hells, which are the afterlife most people think of, and Oblivion, which is religious shorthand for "that thing we don't understand that happens after a soul leaves the Nine Hells." These two layers are separated by a barrier called the Veil, which no one is able to penetrate (except possibly Eli). Collectively, the different afterlives are referred to as the Realms Beyond.
The Nine Hells were set up to trap the soul on its normal progression through the afterlife, to take the magical power within the soul and feed it to the daedra who ran the hell the soul was placed in. Since their creation, all mortal souls, no matter how good or evil the person was in life, pass through the Hells.
Most mortals take the following progression: Life -> Death -> Astral Plane -> Nine Hells -> Veil -> Oblivion
The only known exception are the elves. Ba'al was not able to construct the Hells in a way that could trap an elven soul, so they take this progression: Life-> Ephiphany -> Death (chosen after Ephiphany)-> Veil -> Oblivion
It is not known what happens to the souls of Dragons, although if Ba'al could not catch Elves in his trap, it would be reasonable to assume that dragons likewise have been free of the Hells.
It is not fully known what happens to the souls of aedra and daedra when they are killed (which is the only way known that they can die). While it is clear that their power and influence pass onto the individual that killed them (for example, Talia inheriting Lilith's powers and spheres of influence), nothing is known what happens to the rest of the soul. And no one can get into the Nine Hells to check if the soul of the dead god is caught there. Likewise the passing of the souls of celestials and fiends who died as a result of the Great War are also unknown.
Upon death, each soul automatically lands in whichever Hell it deserves; priests speak metaphorically about the "weight" of evil deeds dragging souls down into the deeper layers, while good deeds help to elevate souls. The daedra lords could not control which layer a person ends up in unless the person has sold his soul to one of them; the process is entirely mechanistic, and while the daedra maintain the soul-machinery of the hells they cannot redirect the flow of soul-traffic. Each soul lingers in its particular Hell until it has exhausted whatever karmic balance holds it within the bounds of the universe as we know it; souls whose energy is exhausted more rapidly (e.g., by being consumed by a fiendish creature) will pass more quickly out of the Nine Hells and into whatever lies beyond. No one knows what lies beyond — religious types call it Oblivion — but it may be rebirth, nirvana, reabsorption into the essence of the All-Father, or some "true" afterlife that is beyond the realm of human (or daedric) understanding.
In the end, then, the Nine Hells are not eternal reward or eternal punishment. They are simply the cosmic equivalent of a hydroelectric dam, designed to trap escaping souls and extract from them every erg of useable energy before they pass beyond the Wall into Oblivion. Since the process can take centuries, however — and the Nine Hells are fairly well-understood, while Oblivion is not — so most people think of the Nine Hells as "the" afterlife.
There Ain't No Coming Back1
So, how did you get someone back whose soul has fallen into one of the Nine Hells? Since Metamor started as a fantasy setting with strong D&D roots, this was a very valid question. (Considering that Raise Dead was a only a fifth level D&D cleric spell in 3.5…)
It was not easy. In fact, it was so hard that even before the Day of the Starchild most people considered it impossible.
- First, you had to know the True Name of the soul in question, just so you can find them. That isn't always an easy task where mortals are concerned.
- Second, you had to bargain with the Daedra Lord who controls the level of hell in which the soul resides. The cost of buying back a soul was high (in D&D terms, assume a cost of one major geas for every three Hit Dice the soul had. Souls also lose Hit Dice over time as their life force is drained away by the machinery of the Nine Hells; this may be painless, as in the First Hell, or utter agony, as in the Ninth.)
- Third, you had to have a body to put the soul back into — which means either displacing an existing soul from its body, or creating a soulless body with magic, putting the soul into some kind of automaton, or having kept the original body alive by some magical means.
- Fourth, you had to do all of this without employing any of the forbidden books of the Necromancers, which was a capital crime in the eyes of Aedra and Daedra alike.
- Lastly, you had to do all of this before the soul was reduced to an unusable state by the forces of the Nine Hells — which might take centuries in the First Hell, but only hours or days in the rendering plants of Agemnos's Eighth Hell.
As a general rule, dead meant dead. A person who died wasn't coming back without the sort of effort that inspired bards to compose epic poems, so you had to have some insanely committed and powerful friends in order to do it — friends where were willing to bargain with the daedra lords in exchange for your life. Needless to say, the number of people who did it was very, very small.
Now add the events of the Great Fall to this process. The Daedra Lords are no longer in the Hells to bargin with you… so you can't buy the soul back. The Axis between the planes is broken, so you can't travel there. The lore of the Necromancers is almost completely lost.
With those factors in mind, there is no means to raise a person back from the dead. Any attempts may actually call something… else into that body, even if the soul by some chance was lost and not within the hells but haunting a location (because there isn't enough of the soul to bring it back).
She's Only Mostly Dead2
There is one individual known who… sort of died. Talia. Her soul was removed from her body with a soul gem, but her sister Raven kept her body alive by magical means. Seven years later, the soul was then replaced back into the body with considerable magical effort. Talia was insane (by virtue of being trapped in that gem with no outside stimulation), although it took time for everyone to recognize it, then even longer to figure out just how to restore her sanity.
It's been a topic of debate among scholars if this means that Talia died at all (since her soul left her body) or she never died (because her soul never went into one of the Hells before her soul was restored to her body).
Author's Notes
While it is not possible to resurrect a person who has died, spirits residing in the First Hell may be called back into the Dreamlands for a short time by Nocturna. The longer the soul has been in the First Hell, the harder it is for Nocturna to call them back, and she will usually require some sort of focus that is connected to the character. A soul who is visiting the Dreamlands may appear in the dreams of living characters to whom they have a connection.
Another way that ghosts can tarry is if they are bound to something in the mortal realm, such as Janus's father, who was bound to the sword Elemacil. Such a ghost can be facilitated to move on to the Realms Beyond, but without necromancy they cannot be restored to life.
Sources: email from RavenB regarding life and death, and the heavens/hells, in Metamor Keep "The High Cost of Dying"
