Since prophecies are central to the Keepers' work, Caduca plays a very important role inside the organization. Thus, even the Keeper leader listens intently to her advice. 'Caduc-' is a Latin root, standing for 'old', such as in the word 'caducous'. In truth, the old woman is younger than she looks, as the glyph interpreting has aged her rapidly, an effect which restricts the amount of knowledge and power any single Keeper can obtain from studying the Glyphs along his life (this, in fact, limits their power). She replaced the aging Interpreter Diocen in the Keeper's history.
Interpreter Caduca first appears, along with Gamall, in Thief II: The Metal Age, during the first cutscene of the game. She has the ability to read the prophecies through a golden light that manifests from the tip of her fingers when touching the glyphs. Despite that, she was able to read the books directly during Thief: Deadly Shadows. She plays a crucial role in Deadly Shadows, where she is killed by The Hag, disguised as Gamall, the female child who translates the alien words spoken by Caduca as she reads the prophecies aloud.