Transubstantiation

"I awoke upon an endless shoreline made of the bones of all the creatures in creation, and traveled for eternity towards a horizon I could never reach. The waves fell upon the shore like dreams. Flashes of worlds and lifetimes came with each crest, and crash. The foam of that sea were all the possibilities, and choices in life; From the smallest and most carefree decisions of every morning, to the soul-wrenching debates that I had spent my life wondering the reprecussions of. It was both heaven, and hell. A limbo of a kind that felt soul-shattering, and when it seemed I finally could journey no more through that spirit-washing glimpse into the life I had once lived... a vessel arrived to ferry me to the next of what would become many trials, and ordeals of my soul."

— Passage from the 'Journals of the Resurrected'

The House of Fear Itself

Many of the details surrounding the mechanizations of death, and the transubstantiation of the soul remain hidden to the mortals of Orr, but in this world of divine magic and planar gateways, there is more known than unknown. Ressurection is a rare, but not impossible feat in this world, and reincarnation is a supernatural fact of existence. Thus, there are many accounts of those who have returned from death, or have been able (with magical assistance) to recall their former lives and the journey their soul embarked when it was jettisoned from this world.
What is adamantly clear from these tales is that the moment that the soul is delivered from its mortal body, it is flung into a limbo space where time ends. Where a moment can last for an eternity, and a lifetime can flash by in an instant. In this limbo the soul is confronted with its choices, and given some limited insight into how each choice formed the chain of events that became its existence. There is no judgement passed in this place. It is simply a trial of observation. An accurate, ominescent account of one's life lived upon the world of Orr.
It is believed that this place, this... space... is a realm known only as "The House of Fear Itself." A legendary sepulcrum belonging to the twins, Mannec and Narsis. The House of Fear Itself is the realm of the ego, and the id of all mortalkind. The source point of every fear, every ambition, every desire, and every impulse that makes mortals 'sentient' and higher minded than beasts, and monsters. It is a place of unending terror, and trauma whose wallpaper is our own mind, whose ceilings are our own thoughts, and whose ground are our own pride. Very few mortals have ever stepped inside the House before death, and those that have often are driven mad with realizations.

The Ferry, and the River

What triggers the arrival of the ferryman is unknown. Some of the resurrected have said that it was only when they had deeply accessed all of their actions in the House of Fear Itself that the boat arrived, while others have plainly spoken of it being there before they had even tread a step through that demi-realm. Regardless, the boat, and its ferryman are no ordinary beings. They are cosmic constants that existed before life, or death. Some say that the ferryman was the first living thing to die in the universe, and without a home, he chose to shepherd the souls of all those who came after him towards their final destinations. However, many of the ressurected have spoken of conversations with this being that indicate far greater powers, and responsibilities...

"I asked the ferryman what happens when an Endless dies, and he said that he returns them to the black between the stars where he found them in the ages before time."
"The ferryman once told me that the river was longer before mortals arrived on these shores. That it stretched further than light can reach, and that with each new soul that is born, it grows shorter."
"On my trip down the river the ferryman mused that when the last living thing in the world died, he wondered if the Old Powers would return to claim what was stolen from them."

— Passage from the 'Journals of the Resurrected'

The true nature of the ferryman may never be known, but upon his boat a soul is taken down the River of Crux. There are many pathways in this river. Pathways which only the ferryman can chart. Those who fear their final destination may, and often do, attempt to leave his barge and plunge into their depths. This is il-advised. Those souls which leap into the water's depths may one day find their way back to the world, but only as a spirit, wraith, or other undead monster, and the ferryman shall never again guide them back to the safety of their final home in the outer planes.
There are tollbooths along the River of Crux. Gateways which require the soul in question to forfeit some part of themselves. Often these tolls are payed with memories of their former life. Treasured memories are the most valuable currency.

"It's strange to think that a murderer's memory of his favorite kill holds the same weight as a mother's memory of her first child being born on the River of Crux. 'Makes you wonder what the Endless truly value in the end, doesn't it?

— Aristor, Philosopher

At the end of each of the branchways of the River of Crux, a soul will ultimately be delivered to the altar of Carthus, the Endless of Death.

Soul and Feather

At the altar of Carthus a soul's mortal form is ripped down to its flame. Flesh is ruined. Muscles torn. Skeleton broken. Guts, and vitals plucked. Beyond this point there can be no resurrection. Once a soul has been stripped, it is beyond the works of magic to return. The soul is then lifted and placed upon a scale against the weight of a platinum feather that once belonged to the heaven-dragon.

"Evil may thrive in a world of coin, and power, but evil weighs on the soul. Fattens it. And when it is weighed on the scale of the Endless, there shall be lament."

— Ezkrael, Cleric of Carthus

What happens after the soul is weighed is uncertain. Many believe a dark soul is cast into the depths of Hades to be tormented by Devils, Demons, and fire forever; And that a lighter soul is taken into Elysium to be washed, and cleaned by the Seraphim, and Solars of that realm in the waters of Atrium Sol. It would be a more simple, and perhaps a 'kinder' world if such were true... but it is fact that dark lives that were lived on the world of Orr have been reborn, and merciful, loving souls have never returned. Perhaps there is a need for evil in this world. Perhaps there are cycles which the fates have ordained must continue again, and again for some unknown pursuit.

Rebirth

Those souls that do reach Atrium Sol, are cleaned by the hands of angels and washed in the rivers of life where all souls are born. If they retained enough of who they were in the crossing of the River of Crux, the angels may deem to return them with those memories, and insights. They are born again, in a new age, retaining those talents, abilities, and aptitudes that they once learned, and possessed. Thier memories will be buried, and subdued beneath the new experiences that they earn in the world on their next pass through the cosmic circuit... but every so often, they may surface, in the form of dreams, and Déjà vu.
These reincarnated spirits are often identified as prodigies of their time, or heroes who grow more in strength, and capability in a fair few months than some warriors and mages do over lifetimes of study, and practice. It is, however, a difficult thing to prove with any certainty. Certain magical arts have been created to help ascertain the past lives of the reincarnated, but the validity of such magic is highly disputed.

"It is customary in the world of Orr that grave markers for the dead be dedicated to the Endless which guided the soul to their passions in life. The marker of Anser, is often a book, or a ring inset with many keys. Baltizan's followers favor the sigil of an anvil, or a clock. Carthus, the endless of Death, bares the sigil of a tree. Delhira's followers often carve masks into their burial stones. Freyalise's death sigil is the cornecopia. Gozrah's followers carve the sigil of the storm, and the rains. Kassandir's followers often have the weapon they favored in life inscribed upon their tombs. The mad followers of Mannec and Narsis prefer simple flowers. Okondu's death sigils are simple ripples upon water. Pondera's death sigil is the strand of fates being cut by scissors. The worshippers of Sethex carve the faces, or prints of the monsters who slayed the fallen. Tybrus' death sigils are simply crosses, representing the space and time where the fallen have passed over. Varissia's markers are of snakes, and hearts. Yazmin, Endless of Peace and mercy, is represented by doves. And those drawn to Zalamand, Endless of Secrets and rebellion leave no markers at all.