The Rat's Teat Boys are a criminal gang that operates in the Varisian city of Korvosa. They are something of a local legend—a gang consisting entirely of wererats, who go on occasional "recruitment drives" in which they inflict citizens with lycanthropy.1
In fact, the gang are all too real, and are one of the many groups in the city to be on the payroll of House Arkona. They patrol the sewers and the Vaults under Old Korvosa and occasionally slip across onto the mainland for moon-lit crime sprees. Some of the gang have managed to maintain normal lives on the surface, only joining up with the others when the moon is full.
The Rat's Teat Boys view themselves as a family, and consider themselves the voice of the city's wererat population. They revel in their status as lycanthropes, and those contracting the disease in the city are offered the chance to join as soon as the gang learns of their condition. Those who turn down this opportunity are hunted down and killed. To date, only one "independent"—a shopkeeper-turned-wererat called Samp—has managed to escape their clutches.2