A soul is the essential metaphysical life energy of a living creature created by primordial deities to filter the multiverse's fundamental life energy. Innately unaligned, each soul is created in the Positive Energy Plane and (with few exceptions) traverses the River of Souls from its creation to a mortal vessel, then returns to the river after their vessel's death to reach the Outer Sphere.
Religious myths vary on the subject of how souls are formed, though in truth, few deities have any power over their creation. Unaligned souls grow from sparks of unaligned potentiality in the Positive Energy Plane, planted like seeds by unknown means from unknown locations and tended to by the plane's jyoti and manasaputras as the souls ripen like fruit atop massive, amorphous tree-like structures. Mature souls are collected and released by jyoti into portals, focal points, and planar vertices to the Material Plane, to be received by children of creatures as they begin their lives.
At the end of the creature's mortal life, its soul leaves its body and manifests in the Ethereal Plane, beginning its journey with other souls via the River of Souls—a path that travels through the Elemental Planes toward the Astral Plane, with few (and often tragic) exceptions. Mutual interest in the traffic of souls prevents deities from disturbing their transit across the River of Souls, though other agents occasionally intervene. The goddess Pharasma judges these souls at her spire in the Boneyard for their distribution to patron deities or Outer Sphere planes, where she serves as the final arbiter over contested souls.
The souls of atheists and agnostics pass through to a plane related to their principles, but dissident souls that refuse Pharasma's judgment and failed souls that never exhibited faith or passion in life never progress. Pharasma dispatches them to a dormant existence in the Graveyard of Souls or roam it in distress, wander the Astral Plane, or are chosen by Pharasma to return to the Material Plane as a reincarnated being. The souls that never leave the Graveyard eventually break down into dormant quintessence called soul debris, which comprises the spire atop which the Boneyard stands.
Souls that travel to a patron's realm are known as petitioners who await their final judgment at their patron's hands. In some cases, these souls earn eternal peace or meld with quintessence to become outsiders in their patron deity's plane. In others, they are rejected and sent to serve an infernal punishment. Their forms might change depending on their patron or become more idealized versions of their mortal selves.
Fey are formed from the soul energy left in the wake of new souls' passage through the First World on their way to the Material Plane.
Given sufficient belief in an alternative path, a soul can forego the River of Souls for a different fate, such as reincarnation. Such diversions are ultimately temporary, however, and at some point the soul attempts to reach the Boneyard.
Pharasma is also the goddess of fate, and sometimes holds a soul in the Boneyard for its mortal form to be resurrected when she knows it has not fulfilled its potential.
Certain spells can trap souls, preventing their progression into the afterlife.
Spiritualists call and bind a soul from the Ethereal Plane, granting it an ectoplasmic physical form.
Certain creatures, such as Tieflings, can consume and destroy souls.
Tieflings trade for or steal souls for eternal servitude or to use them as currency.
Eternity's Doorstep is said to be a soul trap capable of sucking the remaining souls from Undead who still cling to them.
Unclaimed souls not taken by formian clans in Axis sometimes become axiomites who retain their mortal forms.
A Lich stores their soul in a phylactery, and regenerates their physical form as long as the phylactery is intact.