Rendan took over the band after having his injured, older brother Gelmar killed. They all worked for "Master Dark." Rendan had a younger brother as well, but after displeasing Master Dark, the mage had the brother chained to a cliff-side where carrion birds tore him apart every day, eating his flesh, which regrew each night. When the wind was right, the bandits could occasionally hear his screaming.
Rendan and his band were one of the many groups of bandits Master Dark had out searching for Herald-Mage Vanyel. Rendan was the one who found him. They captured Vanyel in an ambush, armed with anti-magic powders and magically paralyzing darts. After dragging Vanyel back to their hall, Rendan joined his men in beating him, and encouraged them to rape him repeatedly.
When a temporarily insane Vanyel was finally freed, he killed most of the bandits, torturing several of them. He was forcing Rendan to gut himself when Stefen and Yfandes appeared on the scene. Stefen persuaded Vanyel to stop, and in the ensuing meltdown, Rendan escaped. Given that he was running into the snow without a cloak, weapons or supplies of any kind, it is doubtful he survived the night.