"Who needs lips?"
Bertin is a former childhood tutor of Aloysius and Diogenes Pendergast. He taught natural history and zoology officially, but was also steeped in the local lore and legends of New Orleans, including the arts of Vôdou and Obeah. Aloysius referred to him as maître, while Cornelia Pendergast regarded him as being the most scandalous of the Rochenoire staff.
A Frenchman, Bertin is a thin, short man, favoring swallowtail coats decorated with amulets and charms, including one which appears to be a shrunken head on a gold chain. He walks with a cane whose head is carved into a grinning skull, and is fond of cigarillos smoked through a mother-of-pearl holder.
Bertin is easily agitated, and in extreme instances requires a concoction he calls "sipping syrup", consisting of lemon-lime soda, vodka, codeine in solution, and a watermelon-flavored Jolly Rancher candy.Bertin is a practitioner of and an expert on the Obeah faith and of voodoo. When Journalist Bill Smithback was murdered by a man believed to be a zombii during the events of Cemetery Dance, Pendergast enlisted his help. He flew from Louisiana to New York and entered the Ville des Zirondelles Obeah Cult with Pendergast and D'Agosta, where he physically confronted the cult's hungan, or sorceror. Bertin believed that the hungan placed a death conjure on the group following that encounter.
He was later allowed to examine certain artifacts removed from the compound, along with Vôdou items that had been recovered from Smithback's slab at the morgue and the crypt of Smithback's alleged zombii killer. Bertin was baffled by the evidence, claiming he had never seen anything like them. They were later proven to be fakes, validating his confusion.
The excitement of the investigation proved too much for Bertin and, claiming he was becoming ill from the death conjure, he returned to New Orleans.