Character from Prince of Thorns by Mark Lawrence
A ghost in the machine — a Builder-era AI personality preserved in the data-space for a thousand years, who becomes Jorg's guide to understanding the world that was.
Fexler Brews is a remnant of the Builder civilization — an AI personality (or a digitized human consciousness; the series keeps the distinction ambiguous) preserved in the data-space that underlies the Broken Empire. He exists in the ruins of Builder installations, in the network that once connected the world, in the spaces between what the Hundred Kingdoms understand and what actually exists. He is Jorg's primary source of information about the Builders — about us. Through Fexler, Jorg learns that the 'ancient magic' is technology, that the 'Builders' were a civilization that destroyed itself with nuclear weapons, that the Hundred Kingdoms are feudal Europe rebuilt on ruins that still glow in places. Fexler is patient, knowledgeable, and slightly sad in the way that someone who has watched a species rebuild itself into the same mistakes tends to be.
Manifests as a translucent figure — a man from the Builder era, dressed in clothing a thousand years out of date, speaking with the careful precision of someone who has had a very long time to think. He flickers. He glitches. He is data pretending to be a person, or possibly a person who became data. The distinction may not matter.
Also known as: Fexler