OF DEMONS, DEVILS & THOSE IN-BETWEEN

THE DEMON/DEVIL DICHOTOMOUS DELINEATION
In D&D, demons and devils are beings of a wholly different nature & origin. Though both are embodiments of evil, they’re further separated by their opposing allegiances to either Law or Chaos.
On Gothenya, the terms are nothing but slang, and to some degree, essentially interchangeable. Most commonly held to the moniker “Demon” are the cousins of the Vala’suun, the Vu’un. Most are chaotic in allegiance, though there are more organized kingdoms of such creatures of a more lawful bent. Vala’suun tend to run contrary to this, with the Solti holding to a strict doctrine of law (warped or depraved as it may be), and the “free Sidhe” of non-servitor Kelti skewing more chaotic.
There are essentially an infinite variety of Vu’un, be they called demon or devil. Their biological origin, the juncture at which they deviated into a species distinct from their cousins, is connected to an intensification of trafficking in the Dark Arts. Those more organized sat on the thrones of several Baronies subservient to that of Neishmehil (the real one). Seeing no other way to better their positions, due to the stranglehold of the Solti “Court of Winter,” they turned to a corruption of the Eret Si’nu in order to change their fates.
It wasn’t actually this turn that really catalyzed the split. It came after the Solti, through their network of Royal Shadows (crown spies), discovered their intent and banished their entire country from the realm.
They brought war to the Vu’un, with no quarter offered to the quickly overwhelmed defenders. They were forced to run, those who survived. The only direction the Solti would not follow was down.
After establishing a far weaker, yet somewhat recognizable subterranean kingdom, they set to finish what they began previously on the surface. But now, in desperation from their fatal misfortunes, with significantly less regard for their own safety. After several millennia, the Vu’un (Sidhe, similar to the Vala’suun) shook off much of what made them fey. Replacing their familiar traits with those more conducive to servants of Chaos.
Laws and the lawful can still be evil. And those attending to chaos might still find structure and rigor within their hierarchies.
Perhaps the biggest, or truest, difference between demons and devils with regards to Gothenya and its surrounding universe, has more to do with the nature by which Vu’un are created.
True Vu’un are essentially devils. They can only be made from entities originating on Jeis’suul. Sidhe turned to chaos.
Demons, on the other hand, are often corruption personified in the form of mortal mutations. Some even from The Churn. They constantly seek to increase their ranks, and propagate far faster than “true” Vu’un. In fact, although they are often mistaken or associated with the Vu’un, what we would consider actual demons are not related to them in the slightest. The Vala’suun are far closer in nature to true Vu’un (closer to devils) than these so called demons will ever be.
It is important to note that not all mutants are demons. The Urtlan, for instance. What specifically makes a demon what it is has to do with affiliation. And here is where they have a connection to the real Vu’un. For those mutants who, in the midst of transformation, give themselves up and dedicate their existences to Chaos… those are the poor souls who truly deserve the mantle of demon.
For superstitious humans, who see all dimensional visitors as abominations, it’s easy to see how the distinctions become convoluted.
Demons created in this fashion are questionably possible to summon. Depending mostly upon where they lair.


SUMMONING/THE GOD-DEVILS OF MAN
As far as Vu’un and Vala’suun (Devils and Elves), the Vu’un have the taint of all dimensions far more prominent in their blood, for having trafficked so with the outer limits of the Eret Si’nu. This makes them the most likely of all the species discussed herein to answer or succumb to a summons.
The Vala’suun (specifically the Solti, but also affecting the Kelti) took great pains to ensure their blood could never be swayed. Upon realizing that to a great degree the Vu’un were no longer masters of their own fate, they experimented upon themselves in order to disallow any potential summonings. In doing so, they had no idea that they were inflicting upon themselves an internal barrier, making it quite difficult for them to traverse the outer dimension planes - without the means of artificial transport, at least.
This would return to haunt them in the ages since many were abducted by the Ulta and forced into servitude. Here, on the “Material Plane of the Third Relation”(dimension), they cannot “shift” back to Jeis’suul, as they once might have been able to accomplish. Trapped they are, and damned as well. It’s uncertain, but this self experimentation might have also led to the infertility that currently afflicts them in total.
The Kelti are more suited for dimensional shifting, though they do not possess the magic Art necessary to perform this without assistance. They certainly won’t find any from the Solti. Their jealous and spiteful masters would never aid their “indentured” servants in a mass exodus back to the paradise they themselves are seemingly banished from.
Some would say that the Ulta, particularly those pushing themselves to be “gods,” are more accurately “on the path” to becoming a new variant of (non-Vu’un) “devils.” This, due to their development and spiritual sacrifice being more than a bit similar to that of the outcast Vu’un.
For their part, the Vu’un still retain a degree of free will, and upon (rare occasions of) birth, the Vu’un spawn must still choose whether or not to embrace their chaotic inheritance. Those who don’t are cast out or, barring that, put to the sword. At least with regards to those within Maliborge, the “Unholy City” beneath the surface of Jeis’suul.