Brehen, also known as the Cat of Iello, was a rogue witcher from the Cat School. During his training he underwent mutations that were not entirely successful. Like most other Cat witchers, he was known for his cruelty and had no qualms about killing people. At The Wild Boar and Stag inn he confronted Geralt of Rivia, believing the Wolf wanted to go to King Foltest to take the striga contract. Brehen, known for his wily ways, took a hostage to force Geralt to duel. He eventually failed and was forced to leave. During their conversation, Brehen implied that he was no longer welcome at the Cat School and believed that Vesemir had issued a death sentence on him.
The Iello Massacre
The massacre at the town of Iello, widely accepted to be the handiwork of the witcher Brehen, forever after known as the Cat of Iello, is but one of many infamous episodes in the history of witchers. Due to its widespread notoriety, it is often compared to the dramatic events which took place a few years later at Blaviken on the Arc Coast. There, in broad daylight, the witcher Geralt strode into the town market and murdered six men and a woman in cold blood, thus earning the enduring sobriquet of the Butcher of Blaviken. Although, he was largely forced into this, having to choose between killing a sorcerer, killing the aforementioned 7 people or letting them hold the Blaviken market hostage.