Demonic

Demonic is spoken by Demons, but also those who wish to invoke Demonic powers, magics, and other similar dark or evil ends. It does not have words for "nice concepts" such as "love, compassion, empathy, or kindness" for example.

Writing System

The Demonic Alphabet is primarily Runic in nature, with the runes written in a clockwise circular pattern, unless they are connected via lines, and in that case, the runes are linked by the lines, and you start with the bottom most rune, and each one modifies (if possible) the meaning of the other runes. Rarely, it exists as a straight line of runes, and in that case is read left to right.
All demonic runes consist of slashes, circular patterns, lines, dots, or a combination of them, perfect for being written with blades or claws.

Geographical Distribution

Mostly spoken by Demons from The Abyss, it does not have a widespread use, but is known by those who would consort with demons.

Phonology

While Demonic doesn't have sounds directly change depending on words like Common does, Demonic has the unique effect of sounding darker and more guttural the longer a phrase is, the sounds themselves becoming more and more guttural as the sentence continues. It is for this reason that Demonic often is written (if in a line format) with commas rather than periods, and has a rhythmic structure, with pauses being used to continue the "darkening" of the sounds as the speech continues. It is not, however, considered lyrical by any means.

Morphology

Demonic does not have any specific bound morphemes, but instead almost always has static words.

Syntax

Syntax's are almost non-existent, save for possessive and the angelic past tense "yed", though that seems to be taken more as a taunt than an actual word used in communication between Demons. 
Possessive: -kek -> Ballathiagar-Kak Imthirx - (Common) Ballathigar's Spear

Vocabulary

The Demonic Language Vocabulary hasn't changed since shortly after the Dawn of Creation, and the languages is imprinted on any full blooded Demon and Devil, and can be awakened using a ritual or specific spell in half-demons or half-devils.
All words are created and modified from base concepts, and grow from those base concepts. For example Campfire would be "Infernpaal" (Infern = Fire and Paal = Place). This is why words that mean "love", "empathy", or "Kindness" don't exist.

Phonetics

Demonic sounds are harsh and guttural sounds, and often require the flashing of teeth to properly form the sounds. It is nigh-impossible to soften the sounds of the words, and likewise (due to the more guttural sounds) extremely difficult to whisper them without someone overhearing them if they are nearby. 
Those who hear it often describe a sort of mental discomfort from hearing the words uttered, as if a harsh buzz or a headache was caused by the mere utterance. There has been observed cases where those more sensitive or empathetic bleed from their noses and/or ears.

Tenses

Given that Demons are truly immortal, they instead use specific words to indicate past, present, or future, though this is generally rare since to them, they prefer to have statements and let the listener decide on context of when it is happening.

Sentence Structure

Demonic tends to be fairly straightforward given that it rarely has any sort of time related events and instead simply is. From a structure perspective, it is either Simple Sentence Structure or Compound Sentence Structure, with the Compound conveyed by lines (if written circular), commas (if written in line form), or pauses (if spoken).

Adjective Order

The Adjective Order of Demonic is:

1. Determiners
2. Age
3. Origin
4. Color
5. Shape
6. Size
7. Material
8. Observations

Dictionary

12 Words.

Common Phrases

Lithan Kek Yeer

Light Take You (Demonic insult to other demons)

Xith Belgax Infern
Darkness Chains Fire (Demonic saying about corrupting passions or something 'good', and turning into something dark)