Brehen, also known as the Cat of Iello, is 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 Boar and Deer 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 implies that he is no longer welcome at the Cat School. He also believes that Vesemir issued a death sentence on him.

"His hair was gray as ash, temples interspersed with snow-white stripes. And bright yellow eyes with a vertical pupil. On his neck, under his shirt dehulled, glittered in the candlelight silver medallion. The head of a grinning cat."
- Storm season