Now take this sword, this Treaty-Blade. Occurian seal, mark of your worth. Cut deep the Cryst and seize your Shards. Wield Dynast King's power! Destroy Venat!
- —Gerun to Princess Ashe
In ancient times, Gerun granted the Sword of Kings to the hume Raithwall to become their proxy in determining the course for Ivalice and manipulate history to their own ends. Raithwall obtained three shards of deifacted nethicite from the Sun-Cryst, the Occuria's magicite of power, to become the Dynast King, and played his part well in Gerun's ploy.
700 years later, the heretic Venat trespassed into the hume realm, granting them means to create their own kind of nethicite and control their own history. Gerun turned to Princess Ashe, the descendant of King Raithwall, to destroy Venat and the Archadian Empire - the judgment for making imitations and trying to control their fate.
Luring the princess with a specter of her dead husband, Gerun hoped to fuel Ashe's hatred for the Empire enough to have her destroy it. The princess sees through Gerun's motive, and refuses to be manipulated. Instead, she has the Sun-Cryst destroyed breaking the power of the Occuria over Ivalice.
Gerun is voiced by Bernice Stegers in the English version and Seiko Tomoe in the Japanese version. Occurian speech resembles an archaic, poetic form of Received Pronunciation English, which is noticeably absent of particular rhotic vowels in both speech and writing. Gerun, like the rest of the Occuria, speaks in iambic tetrameter, a commonly used type of metrical line in traditional English poetry and verse drama.
The decision to use metered verse with an unusual rhyme scheme came about as a solution to the problem presented by the voice processing used for the Occuria in the Japanese. The multiple layers of voice in the Japanese had an otherworldly sound, but made it difficult to discern what was being said though helped by the on-by-default subtitles. The localized version has subtitles off by default, so the translators needed something else to differentiate their speech.
Because Gerun (and the rest of the Occuria) are immortal, its name may originate from the Ancient Greek word geron meaning "oldest".
The word gerun (pronounced as "grr-roon") means "recoil" in Malay. It is also the root word for the word menggerunkan, meaning "the most startling", "the terrible" or "the horrifying". It may also be translated as "awesome" or "beyond great", but that is uncommonly used.