Vowel of Derangement

The "Vowel of Derangement," known to arcanolinguists as the close front rounded vowel, has an dark and eldritch history in the land of Istria.

The Vowel was first pronounced by the secret god Ktul, in one resounding and bloodcurdling note. From this note emerged the whole of Ktul's children, a dark and twisted horde produced from the nightmares of creation itself. Ktul continues to pronounce this vowel, and all his children sing in harmony with him. For this reason, the pronunciation of the close front rounded vowel is forbidden almost universally by all intelligent beings of non-chaotic alignment.

Effects of Pronunciation
No one survives pronunciation of the Vowel of Derangement and preserves their sanity or freedom. Precisely what becomes of their minds is unknown, though it is widely accepted that their bodies become the servants of Ktul, forever condemned to join in his discordant song.

Impact on Istrian Orthography
Because of the horrible effects of the Vowel of Derangement, any vowel, vowel combinations, or vowel markings that might indicate its pronunciation are forbidden. In the common script, these include (ü), (ű), (iu), (yu), and sometimes (u) itself. Many Istrian asylums are filled with entire wings of gibbering maniacs who endlessly scrawl "üüüüüüüüüüüü" in some combination of blood, feces, and urine on the walls of their cells and whatever paper they are given, sometimes even scarring the fell (ü) into their skin.

The graphemes of all languages in the history of Istria ever known to be associated with the Vowel of Derangement are recorded in the horrendously evil tome De Vocales Dementiae ("Of the Vowels of Madness"). Its author is unknown.

The Name of Ktul
Ktul's name is properly pronounced with the Vowel of Derangement, but it is never written in a way to indicate this pronunciation (except in the writings of the truly evil) for fear that an unwitting reader will pronounce it properly and descend into madness.