Roth was known as Rat to the children of the Black Dragon guild in the Warrens. He was a sadistic, cunning and ruthless tyrant, with high ambitions. He hated Azoth (Kylar) and did everything he could to make his life a misery. One of his plots was to leave Azoth alone, and punish everyone else. The point was to get the other kids to think of him as a hero, but then Rat could kill him and crush the hope of the others. He was the one responsible for the brutal mutilation of Doll Girl (Elene). Rat is known to rape his victims, and does not seem to mind about the gender of his victim.
Rat was supposedly killed by Azoth. He was drowned in the Plith river, and Azoth cut his ear off.
During the Invasion of Cenaria, it is revealed that Rat is actually Roth Ursuul, the aethling of Garoth Ursuul, Godking of Khalidor. Roth's Vurdmeister mentor, Neph Dada, rescued him from The Plith and swapped his body with that of a big called Roth from the Black Dragon Guild. As punishment for his failure at destroying Azoth, his other ear was burned off. He always believed that Azoth was still alive since Durzo feigned his death for Brant Agon. He is pretty much the same sadistic person, except missing an ear. Roth conspired to be the Shinga, and dispose of Momma K. Roth posed as a rising star of the Sa'kage, and was the guild head of the Red Bashers, under the name Roth Grimson. He had played a gruesome spectacle in which he fed the peasants with soup, while he shot at them with an arbalast. He then hinted to Momma K during a meeting that they were eating "peasant" not pheasant. His sources led him to find Durzo Blint's daughter. He is killed eventually by Kylar, the Night Angel.