Chief clerk to Kallian Publico of Numalia, Nemedia. He confessed to Posthumo that he was without friends and money, an indication that his profession and his life were not that profitable or fulfilling.
His sad career came to a sudden end on the night that Arus the watchman caught Conan after he broke into Kallian Publico's Temple. Promero was dragged into the temple during the investigation. He later collapsed and died with no visible wounds after exiting a room that contained an ancient Stygian artifact.
Promero has been described as "small" and "timid". He was a nervous individual, prone to crazed outbursts.