Mortis

Mortis is the part of the soul that puts the "Mort" in Mortals.  A Mortis is the spark of the divine. It’s closest to what most modern people consider a soul to truly be. It’s what separates people from animals.
Animals, Fair Folk, most plant monsters, elementals, constructs and the like do not have Mortis. Most spirits do not have a Mortis but an Exemplar Spirit, a spirit created from an elevated mortal soul, does have a Mortis. Arguably such being doesn’t have a Mortis. Such a being is a Mortis.
A Mortis is what is meant to be eternal. The Mortis is also what Turoch liked to eat. It’s what Void Demons still try to eat. Undead very rarely if ever try to feed on a mortal’s Mortis though some undead may destroy a Mortis as an accidental byproduct of consuming a mortal’s Heart’s Fire.
A Psyches can live without a Mortis. Can a Mortis exist without a Pysche? Yes…sort of. 
If a soul loses its Psyche, the Mortis literally becomes one with one of the Nine. Some people find the idea of this very comforting while others find the idea of this utterly terrifying. The existence of the Mortis is mostly for theologians and magical scholars to debate. For all a typical peasant knows, the Psyche and the Mortis are the same thing. Most people cannot imagine existing without thinking.

Type

Metaphysical, Divine