Perjour (pronounced /pɜ:ʳʒʊəʳ/) was a scholar in the service of Zaros, first mentioned in the lore Twice Burnt. He was bound to a book that magically transcribed everything he saw, heard and thought, which Zaros would read after every mission he sent Perjour to witness.
Zamorak cast a spell on the book while they were watching Char's performance when she was a dancer, which altered the spell Zaros had placed on it, duplicating the book into Zamorak's possession, so Zamorak could read what was being reported back to Zaros. When Perjour was taken with Zamorak, Viggora, Thammaron, Enakhra and Char on a mission, Zamorak altered the spell again, causing the book to show a different version of events, hiding many occurrences. This alteration was made to help him overthrow Zaros with the Staff of Armadyl, as Zaros would not know of Zamorak's actions, enabling him to plan unhindered.
Perjour was later present during Zamorak's betrayal of Zaros, as seen during Children of Mah, where his nerves caught the attention of Kharshai. When asked by the inquisitor, he claimed to have been sent by Zamorak, who could not divert from his mission, and handed over his book when asked. Kharshai saw nothing suspicious in the book however and let Perjour be, unaware that Zamorak had the real book in his possession.
Perjour died in the caves leading to the Elder Kiln, as it shown in the Journal of Perjour, obtained during The Elder Kiln quest. During his last writings, Perjour stated that he was searching for the Kiln in attempt to raise an army for Zamorak, so it is conclusive that he sided with Zamorak during his rebellion and served him until his death. He also states in his journal that Char died in a cave as well. This cave is explored in the quest The Firemaker's Curse, in which it is made clear that Char did not die as Perjour believed, but survived Zamorak's attempted assassination.